County of Marin Health and Human Services

Influenza Activity Updates

Marin County Department of Health and Human Services tracks influenza activity by analyzing laboratory testing data and visits to local emergency departments for influenza-like illness. The influenza season runs from early October to late May, usually peaking between late December and early February.  During influenza season, we produce a weekly influenza surveillance report that summarizes influenza activity in Marin County, California, and the United States.

Marin

Influenza season is here. Data on influenza testing and influenza-like illness will be posted to this site approximately monthly. This year, Marin County is monitoring respiratory illness activity to indicate potential surges in COVID-19 activity, as well as influenza activity. You can find additional information about respiratory illness and COVID-19 in Marin County here. The best way to protect yourself and others from influenza is to get the flu vaccine. You can find out where to receive the flu vaccine here.

Influenza-like illness activity 

Influenza-like illness (ILI) activity in Marin County is within the expected range for this time of year. ILI surveillance may Emergency department census data from Kaiser San Rafael, MarinHealth, and Novato Community Hospital showed the percentage of visits associated with ILI was 5.1% during week 40 (Sep.27 - Oct.3). See Figure 1 below.

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital Emergency Departments, 2018-2019, 2019-2020, and 2020-2021 Influenza Seasons

 

 

Influenza testing 

During week 40 (Sep.27 - Oct.3),  0 (0%) of the 8 specimens tested for influenza were positive. During this influenza season through October 3, 0 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2020-2021 Influenza Season

 

Respiratory Illness Data

Marin County is monitoring respiratory illness data for surges that may be related to COVID-19 or influenza. The graph below shows data on respiratory illness admissions to the emergency department over the last three years. See Figure 3 below.

Figure 3. Respiratory illness admissions to the emergency department

ed_update_daily_new.pngInfluenza Related Deaths 

There have been no influenza-related deaths of older adults (>65 years old) in Marin County during the 2020-2021 flu season.

Note: Marin County now includes number of influenza-related deaths in our influenza communications. This does not indicate an increase in deaths compared to previous flu seasons, but a change in reporting procedures.

California

Visit the California Department of Public Health’s influenza website here for more information.

United States

National influenza activity was minimal during week 39 (Sep.20-26) 
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website here.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx(link is external). Accessed 10/6/20.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm(link is external). Accessed 10/6/20.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

COVID-19 Update

Regular influenza surveillance updates have been temporarily paused during COVID-19 response. For up-to-date information on COVID-19 and respiratory illness surveillance in Marin County, visit our Novel Coronavirus Surveillance page.

Marin

Local influenza activity continues to increase in Marin County with a spike in activity seen during January 2020. To date, the 2019-2020 flu season has been more severe  than the 2018-2019 season. It is not too late to get the flu vaccine if you haven't already. You can find out where to receive the flu vaccine here.

Influenza-like Illness Activity

Influenza-like illness activity in Marin County has remain elevated levels since early November, with a larger spike in activity seen at the end of January. Discharge data from Kaiser San Rafael, MarinHealth, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was 12.8% during week 10 (Mar.1-7). See Figure 1 below.

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital Emergency Departments, 2017-2018, 2018-2019, and 2019-2020 Influenza Seasons

ili_wk10.png

Influenza testing: During week 10 (Mar. 1-7),  21 (14.1%) of the 149 specimens tested for influenza were positive. During this influenza season through March 7, 512 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2019-2020 Influenza Season

flu_labwk10.png

Influenza Related Deaths: There have been three influenza-related deaths of older adults (>65 years old) in Marin County during the 2019-2020 flu season.

Note: Marin County now includes number of influenza-related deaths in our influenza communications. This does not indicate an increase in deaths compared to previous flu seasons, but a change in reporting procedures.
 

California

The geographic spread of influenza activity in California was widespread during week 9 (Feb.23-29).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website here for more information.

United States

National influenza activity remained elevated but continued to decrease for the third week in a row as of week 9 (Feb.23-29).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website here.

Novel Coronavirus (2019-nCoV): You can find local information about COVID-19 (novel Coronavirus) here.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 3/12/20.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 3/12/20.

Blog Category: 

Influenza Activity Updates

Marin

Local influenza activity continues to increase in Marin County with a spike in activity seen during January 2020. To date, the 2019-2020 flu season has been more severe  than the 2018-2019 season. It is not too late to get the flu vaccine if you haven't already. You can find out where to receive the flu vaccine here.

Influenza-like Illness Activity

Influenza-like illness activity in Marin County has remain elevated levels since early November, with a larger spike in activity seen starting in mid-December. Discharge data from Kaiser San Rafael, MarinHealth, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was 14.6% during week 5 (Jan.26-Feb.1). See Figure 1 below.

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital Emergency Departments, 2017-2018, 2018-2019, and 2019-2020 Influenza Seasons

flu_jan_20.png

Influenza testing: During week 5 (Jan. 26 - Feb. 1),  44 (21.5%) of the 133 specimens tested for influenza were positive. During this influenza season through February 1, 354 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2019-2020 Influenza Season

flu_lab_feb_20.png

Influenza Related Deaths: There have been two influenza-related deaths of older adults (>65 years old) in Marin County during the 2019-2020 flu season.

Note: Marin County now includes number of influenza-related deaths in our influenza communications. This does not indicate an increase in deaths compared to previous flu seasons, but a change in reporting procedures.
 

California

The geographic spread of influenza activity in California was widespread during week 4 (Jan.19-25).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website here for more information.

United States

National influenza activity remained high and continued to increase during week 4 (Jan.19-25).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website here.

Novel Coronavirus (2019-nCoV): The risk from novel Coronavirus in the U.S. remains very low and Marin County residents are at a much greater risk of contracting the flu. You can find local information about novel Coronavirus here.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 2/4/20.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 2/4/20.

Marin

Influenza season is here, and influenza-like illness activity is on the rise in Marin. Positive tests began to increase in September this year and continue to rise. Current data suggests an earlier flu season during 2019-20.

Influenza-like Illness Activity

Flu activity has increased and is within expected levels for this time of year. Discharge data from Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was 8.2% during week 48 (Nov. 24-30). See Figure 1 below. 

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital Emergency Departments, 2017-2018, 2018-2019, and 2019-2020 Influenza Seasons

flu_nov_19.png

Influenza testing

During week 48 (Nov. 24-30), 17.9% of the  specimens tested for influenza were positive.  During this influenza season through November 30, 61 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2019-2020 Influenza Season

flu_lab_nov_19.png

Influenza Related Deaths: There have been two influenza related deaths in Marin County in the 2019-2020 flu season.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California was widespread during week 49 (Dec. 1-7).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website here for more information.  

United States

National influenza activity is increasing during week 49 (Dec. 1-7).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website here.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 12/16/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 12/16/19.

Marin

Influenza season is here, and influenza-like illness activity is on the rise in Marin. Positive tests began to increase in September this year and continue to rise. Current data suggests an earlier flu season during 2019-20.

Influenza-like Illness Activity

Flu activity has increased and is within expected levels for this time of year. Discharge data from Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was  6.4% during week 45 (Nov. 3-9). See Figure 1 below. 

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MarinHealth Medical Center, and Novato Community Hospital Emergency Departments, 2017-2018, 2018-2019, and 2019-2020 Influenza Seasons

flu2_19.png

Influenza testing

During week 45 (Nov. 3-9), 10 (11.2%) of the 89 specimens tested for influenza were positive.  During this influenza season through November 9, 18 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2019-2020 Influenza Season

flu_lab2_19.png

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California was widespread during week 45 (Nov. 3-9).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website here for more information.  

United States

National influenza activity is increasing during week 45 (Nov. 3-9).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website here.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 11/18/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 11/18/19.

 

Marin

Influenza season is here, and influenza-like illness activity is on the rise in Marin. Positive tests began to increase in September this year, and are currently at expected levels for this time of year.

Influenza-like illness activity 

Flu activity is within expected levels for this time of year. Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was  5.4% during week 41 (Oct. 6-12). See Figure 1 below. 

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments, 2017-2018, 2018-2019, and 2019-2020 Influenza Seasons

flu1_19.png

Influenza testing

During week week 41 (Oct. 6-12), 1 (1.9%) of the 54 specimens tested for influenza were positive.  During this influenza season through October 12, 2 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2019-2020 Influenza Season

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California is sporadic for week 41 (Oct. 6-12).
Outpatient influenza-like illness and hospitalizations were within expected levels.
Visit the California Department of Public Health’s influenza website for more information.  

United States

Influenza activity was minimal during week 41 (Oct. 6-12).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 10/21/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 10/21/19.

 

Marin

Influenza-like illness activity has decreased in Marin.  Positive tests have continued to decline since April 2019.

Influenza-like illness activity 

Flu activity is within expected levels for this time of year. Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was 6.55% during week 20 (May 12-18). See Figure 1 below. 

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments, 2016-17, 2017-2018, and 2018-2019 Influenza Seasons

fluaroo.png

Influenza testing

During week 20 (May 12 - May 18), 0 (0%) of the 58 specimens tested for influenza were positive.  During this influenza season through May 18, 499 specimens have tested positive for influenza. See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2018-2019 Influenza Season

flu4.png

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California is normal for week 20 (May 12 - May 18).
Outpatient influenza-like illness and hospitalizations were at expected levels.
Visit the California Department of Public Health’s influenza website for more information.  

United States

Influenza activity was normal during week 20 (May 12 - May 18).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 5/23/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 5/23/19.

Marin

Influenza-like illness activity has increased in Marin.  Positive tests have remained elevated throughout 2019.

Influenza-like illness activity 

Flu activity remains above expected levels for this time of year. Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) was 7.49% during week 14 (March 31 - April 6). See Figure 1 below. 

Figure 1. Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments, 2016-17, 2017-2018, and 2018-2019 Influenza Seasons

Influenza testing

During week 14 (March 31 - April 6), 41 (28.7%) of the 143 specimens tested for influenza were positive.  Of the positive specimens from week 14, 40 (97.6%) were influenza A and 1 (2.4%) were influenza B. During this influenza season through April 6, 467 specimens have tested positive for influenza.  See Figure 2 below. 

Figure 2. Influenza Tests in Marin County, 2018-2019 Influenza Season

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California is widespread during the week 14 (March 31 - April 6).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website for more information.  

United States

Influenza activity remained elevated nationally during week 14 (March 31 - April 6).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 4/11/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 4/11/19.

Marin

Influenza-like illness activity has increased in Marin.  Positive tests have remained elevated throughout 2019.

Influenza-like illness activity 

Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) has increased to elevated levels in March and are above expected levels for this time of year.  

Influenza testing

During week 12 (March 17-23), 30 (20.8%) of the 144 specimens tested for influenza were positive.  Of the positive specimens from week 12, 28 (93.3%) were influenza A and 2 (6.7%) were influenza B. During this influenza season through March 123, 394 specimens have tested positive for influenza.  See Figure 1 below. 

Figure 1. Influenza Tests in Marin County, 2018-2019 Influenza Season

 

 

Figure : Proportion of Visits due to Influenza-Like Illness (ILI):  Marin County Kaisers, MGH, and NCH Emergency Departments, 2016-2017, 2017-2018, and 2018-2019 Influenza Seasons

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint field that includes the following text: influenza, flu, influenza-like illness, pneumonia, or fever/cough.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California is widespread during the week 11 (March 10-16).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website for more information.  

United States

Influenza activity remained elevated nationally during week 11 (March 10-16).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/Influenza.aspx. Accessed 3/27/19.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/index.htm. Accessed 3/27/19.

Marin

Influenza-like illness activity has increased in Marin.  Few laboratory tests were positive in November and early December, however positive tests have increased since mid-December.

Influenza-like illness activity 

Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) has increased to moderate levels in December and at expected levels for this time of year.  

Influenza testing

During week 1 (December 30 - January 5), 32 (24.2%) of the 132 specimens tested for influenza were positive.  Of the positive specimens from week 52, 30 (93.8%) were influenza A and 2 (6.3%) were influenza B. During this influenza season through January 5, 96 specimens have tested positive for influenza.  See Figure 1 below. 

 

Figure 1. Influenza Tests in Marin County, 2018-2019 Influenza Season

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

The geographic spread of influenza activity in California is widespread during the week 1 (December 30 - January 5).
Outpatient influenza-like illness and hospitalizations were above expected levels.
Visit the California Department of Public Health’s influenza website for more information.  

United States

Influenza activity increased nationally during week 1 (December 30-January 5).
For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. hhttps://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/Immu... 01/11/2019.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 01/11/2019.

Marin

Influenza-like illness activity has increased in Marin and is currently higher than in past seasons.  Few laboratory tests were positive in November and early December, however positive tests have increased since mid-December.

Influenza-like illness activity 

Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments showed the percentage of visits associated with influenza-like illness (ILI) has increased to high levels in January and is above expected levels for this time of year.  

Influenza testing1 

During week 4 (January 21-27), 41 (20.3%) of the 202 specimens tested for influenza were positive.  Of the positive specimens from week 4, 27 (65.9%) were influenza A and 14 (34.1%) were influenza B. During this influenza season through January 27, 447 specimens have tested positive for influenza.  See Figure 1 below.  

Figure 1.  Influenza Tests in Marin County, 2017-2018 Influenza Season
Influenza Tests in Marin County, 2017-2018

1Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, and Novato Community Hospital.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California was widespreadduring week 4 (January 21-27).
  • Influenza activity is decreasing but remains elevated throughout California.
  • The overall percentage of influenza detections in clinical sentinel laboratories in Week 4 (23.3%) was lower than Week 3 (24.9%). 
  • Of the specimens tested by Clinical Sentinel Laboratories, 24.9% (1,509 of 6,468 specimens tested) were positive for influenza during week 4. Of these, 829 (54.9%) were positive for influenza A and 680 (45.1%) were positive for influenza B.  Of influenza A specimens subtyped by the Respiratory Laboratory Network, 75.9% were A (H3).   
  • Visit the California Department of Public Health’s influenza website for more information.  

United States

  • Influenza activity increased nationally during week 4 (January 21-27).
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 26.1% (15,427 of 59,200 specimens tested) were positive for influenza during week 3.  Of the positive tests, 76.4% were influenza A.  
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/Immunization/FINALReport_201751.pdf. Accessed 2/06/2018.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 02/06/2018.

Marin

As expected each season, influenza-like illness activity has started to increase in Marin but remains moderate.  Few laboratory tests were positive in November and early December, however preliminary laboratory data show that positive tests have started increasing since mid-December.

Influenza-like illness activity 

Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) has increased to moderate levels in December but remains within expected bounds. 

Influenza testing1 

During week 50 (December 10-16), 14 (11.6%) of the 121 specimens tested for influenza were positive.  Of the positive specimens from week 50, 11 (79%) were influenza A and 3 (21%) were influenza B. During this influenza season through December 16, 64 specimens have tested positive for influenza.  See Figure 1 below.  Preliminary data for week 51 (December 17-23) show a substantial increase in positive lab tests.

Figure 1.  Influenza Tests in Marin County, 2017-2018 Influenza Season
Influenza Tests in Marin County, 2017-2018

1Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, and Novato Community Hospital.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California was widespreadduring week 51 (December 17-23).
  • Outpatient influenza-like illness and hospitalizations were above expected levels.
  • Of the specimens tested by Clinical Sentinel Laboratories, 34.9% (1,824 of 5,220 specimens tested) were positive for influenza during week 51. Of these, 1,469 (80.5%) were positive for influenza A and 355 (19.5%) were positive for influenza B.  Of influenza A specimens subtyped by the Respiratory Laboratory Network, 94.9% were A (H3).   
  • Visit the California Department of Public Health’s influenza website for more information.  

United States

  • Influenza activity increased nationally during week 51 (December 17-23).
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 22.4% (6,373 of 28,394 specimens tested) were positive for influenza during week 51.  Of the positive tests, 86.7% were influenza A.  
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.

If you have any questions or comments please contact:
Lisa Santora, MD
Deputy Public Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/Immunization/FINALReport_201751.pdf. Accessed 12/29/2017.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 12/29/2017.

As expected each season, influenza activity has started to increase in the Bay Area. This week, there have been coordinated county press releases in the region about local influenza activity. The following is a partial Influenza Surveillance Update Report with up-to-date information about recent influenza trends in Marin County. A full Influenza Surveillance Update Report will be released on MarinFlu.org next week (during the week of January 9th).

Clinical Updates

Rapid Influenza Diagnostic Tests can be falsely negative when the prevalence of influenza is high, as it currently is in Marin County.  The California Department of Public Health advises that these tests should not be used for making treatment decisions in persons at higher risk for influenza complications.  Real-time PCR is the preferred laboratory testing method when influenza infection is suspected.  

Marin

Local influenza activity began increasing during the week of December 11th, with a substantial increase in positive influenza tests during the last week of December (December 25-31) (Figure 1). 

Influenza testing1 

During week 52 (December 25-31), 70 (34.8%) of the 201 specimens tested for influenza were positive.  Of the positive specimens from week 52, 69 (99%) were influenza A and 1 (1%) was influenza B. During this influenza season through December 31, 128 specimens have tested positive for influenza.  See Figure 1 below.

Figure 1.  Influenza Tests in Marin County, 2016-2017 Influenza Season
Influenza Tests in Marin County, 2014-2015

1Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California increased to widespreadduring week 51 (December 18-24), the most recent week for which data are available.
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories, 20.8% (808 of 3,886 specimens tested) were positive for influenza during week 51. Of these, 796 (98.5%) were positive for influenza A and 12 (1.5%) were positive for influenza B.  Of the influenza A specimens, 5 (0.6%) were subtyped as 2009 A (H1), 35 (4.4%) were subtyped as seasonal A (H3), and 756 (95.0%) were not subtyped.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity is rising nationally.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 10.4% (1,813 of 17,395 specimens tested) were positive for influenza during week 51 (December 18-24), the most recent week for which data are available.  
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2051%20-%20FINAL%20Report.pdf. Accessed 1/5/2017.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 1/5/2017.

Influenza Surveillance Update Survey

Please take five minutes to respond to our Influenza Surveillance Update Survey:  https://www.surveymonkey.com/r/59N9JDC.

Marin County Health and Human Services is conducting a short survey to determine how providers and other public health personnel use our Influenza Surveillance Update reports to inform their clinical practice.  We are also soliciting suggestions for how to improve the surveillance updates.  Your responses to the survey are anonymous and will only be analyzed in aggregate. 

Marin

During the past month of this influenza season (April 17-May 14), influenza activity continued to decrease in Marin County, with a reduction in both influenza-like illness activity (Figure 1) and the percent of influenza tests testing positive (Figure 2).  Due to the substantial reduction in both positive influenza tests and influenza-like illness, this report is the last of the 2015-2016 influenza season.

Influenza-like illness activity 
Influenza-like illness activity in Marin County decreased during weeks 16-19 (April 17-May 14) in comparison to past weeks of this influenza season.  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 7.8% during week 19.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza Seasonsiliwks1415.jpg

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 
There was a marked reduction in the number of influenza tests conducted and the number of positive influenza tests during weeks 16-19 (April 17-May 14).  During week 19,  3 (11.5%) of the 26 specimens tested for influenza were positive.  Of the positive specimens from week 19, 2 (66.7%) were influenza A and 1 (33.3%) was influenza B.  During this influenza season through May 14, 222 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Seasonlabwks1415final.jpg

PROVISIONAL DATA, SUBJECT TO CHANGE. 

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • Influenza activity is within expected levels in California.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was within expected levels for this time of year during week 19 (1.7%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 19, 6.9% (49 of 715 specimens tested) were positive for influenza.  Of these, 26 (53.1%) were positive for influenza A and 23 (46.9%) were positive for influenza B. Of the influenza A specimens, 6 (23.1%) were subtyped as 2009 A (H1), 2 (7.7%) were subtyped as seasonal A (H3), and 18 (69.2%) were not subtyped. 
  • The geographic spread of influenza activity in California was local^ during week 19.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity decreased nationally during week 19.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 1.4% during week 19, below the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 7.1% (741 of 10,510 specimens tested) were positive for influenza during week 19.
  • ​During week 19, the geographic spread of influenza activity was reported as widespread+ in two states, regional* in seven states, local^ in 19 states and the District of Columbia, and sporadic~ in 22 states. See map below for week 19.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap15.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.  https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2019%20-%20FINAL%20Report.pdf. Accessed 5/25/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 5/25/2016.

Influenza Surveillance Update

Due to decreasing influenza activity in Marin County, we will be releasing our next and last influenza surveillance update report of the season in one month, during the last week of May.  If you have any questions about influenza activity in the meantime, please reach out to Haylea Hannah at HHannah@marincounty.org or (415) 473-6020.

Marin

During weeks 14 (April 3-9) and 15 (April 10-16), influenza activity was decreasing in Marin County, with a reduction in both influenza-like illness activity (Figure 1) and the number of positive influenza tests (Figure 2).  

Influenza-like illness activity 
Influenza-like illness activity in Marin County decreased during weeks 14 (April 3-9) and 15 (April 10-16) in comparison to peak activity observed during this influenza season.  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 10.4% during week 14 and 8.9% week 15.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza Seasonsiliwks1415.jpg

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 
There was a marked reduction in the number of tests conducted during weeks 14 and 15, corresponding to a decrease in influenza-like illness.  During week 142,  10 (17.5%) of the 57 specimens tested for influenza were positive.  Of the positive specimens from week 14, 5 (50.0%) were influenza A and 5 (50.0%) were influenza B. During week 15, 9 (16.4%) of the 55 specimens tested for influenza were positive.  Of the positive specimens from week 15, 4 (44.4%) were influenza A and 5 (55.6%) were influenza B.  During this influenza season through April 16, 210 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Seasonlabwks1415final.jpg

PROVISIONAL DATA, SUBJECT TO CHANGE. 

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

All data have not been received for week 14. Data are preliminary and subject to change.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • Influenza activity is continuing to decrease in California, however, laboratory data indicate that influenza activity is still elevated in some regions.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was below expected levels for this time of year during weeks 14 (2.3%) and 15 (1.5%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 14, 13.8% (362 of 2,617 specimens tested) were positive for influenza.  Of these, 194 (53.6%) were positive for influenza A and 168 (46.4%) were positive for influenza B. Of the influenza A specimens, 28 (14.4%) were subtyped as 2009 A (H1), 6 (3.1%) were subtyped as seasonal A (H3), and 160 (82.5%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 15, 10.7% (227 of 2,113 specimens tested) were positive for influenza. Of these, 105 (46.3%) were positive for influenza A and 122 (53.7%) were positive for influenza B.  Of the influenza A specimens, 16 (15.2%) were subtyped as 2009 A (H1), 6 (5.7%) were subtyped as seasonal A (H3), and 83 (79.0%) were not subtyped.
  • The geographic spread of influenza activity in California decreased to regional* during week 15.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity decreased nationally during week 15.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 2.1% during week 14 and 2.1% during week 15, both at the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 14.0% (2,544 of 18,188 specimens tested) were positive for influenza during week 14 and 13.4% (2,258 of 16,840 specimens tested) were positive for influenza during week 15.
  • ​During week 14, the geographic spread of influenza activity was reported as widespread+ in 18 states, regional* in 19 states, local^ in ten states and the District of Columbia, and sporadic~ in three states. During week 15, the geographic spread of influenza activity was reported as widespread+ in 14 states, regional* in 19 states, local^ in 13 states and the District of Columbia, and sporadic~ in four states. See map below for week 15.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap15.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.  https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2014%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2015%20-%20FINAL%20Report.pdf. Accessed 4/25/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 4/25/2016.

Marin

During weeks 12 (March 20-26) and 13 (March 27-April 2), influenza was still circulating in Marin County.  However, influenza activity is decreasing, with a reduction in both influenza-like illness activity (Figure 1) and the number of positive influenza tests (Figure 2) during weeks 12 and 13.  

Influenza-like illness activity 

Influenza-like illness activity in Marin County decreased during weeks 12 (March 20-26) and 13 (March 27-April 2) in comparison to previous weeks of this influenza season.  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 10.1% during week 12 and 9.8% week 13.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza SeasonsInfluenza-like illness, Marin County, 2012-2015

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 

During week 12,  12 (14.5%) of the 83 specimens tested for influenza were positive.  Of the positive specimens from week 12, 6 (50.0%) were influenza A and 6 (50.0%) were influenza B. During week 13, 14 (15.2%) of the 92 specimens tested for influenza were positive.  Of the positive specimens from week 13, 8 (57.1%) were influenza A and 6 (42.9%) were influenza B.  During this influenza season through April 2, 191 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Season

PROVISIONAL DATA, SUBJECT TO CHANGE. 

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • Laboratory data indicate that influenza activity in California is still elevated, but is decreasing.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was above expected levels for this time of year during weeks 12 (3.1%) and 13 (1.8%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 12, 16.8% (600 of 3,577 specimens tested) were positive for influenza.  Of these, 267 (44.5%) were positive for influenza A and 333 (55.5%) were positive for influenza B. Of the influenza A specimens, 31 (11.6%) were subtyped as 2009 A (H1), 12 (4.5%) were subtyped as seasonal A (H3), and 224 (83.9%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 13, 16.3% (470 of 2,884 specimens tested) were positive for influenza. Of these, 229 (48.7%) were positive for influenza A and 241 (51.3%) were positive for influenza B.  Of the influenza A specimens, 37 (16.2%) were subtyped as 2009 A (H1), 23 (10.0%) were subtyped as seasonal A (H3), and 169 (73.8%) were not subtyped.
  • The geographic spread of influenza activity in California remained widespread+ during week 13.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity decreased slightly, but remained elevated nationally.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 2.9% during week 12 and 2.4% during week 13, both above the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 18.3% (4,022 of 21,959 specimens tested) were positive for influenza during week 12 and 16.2% (3,383 of 20,921 specimens tested) were positive for influenza during week 13.
  • ​During week 12, the geographic spread of influenza activity was reported as widespread+ in 29 states, regional* in 18 states, local^ in two states and the District of Columbia, and sporadic~ in one state. During week 13, the geographic spread of influenza activity was reported as widespread+ in 25 states, regional* in 18 states, local^ in four states and the District of Columbia, and sporadic~ in three states. See map below for week 13.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap07.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.  https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2012%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2013%20-%20FINAL%20Report.pdf. Accessed 4/12/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 4/12/2016.

Marin

During weeks 10 (March 6-12) and 11 (March 13-19), influenza was still circulating in Marin County.  Both influenza-like illness activity (Figure 1) and the number of positive influenza tests (Figure 2) were at levels similar to the past few weeks of this influenza season, excluding a one week decline in both measures during week 9.  

Influenza-like illness activity 

Influenza-like illness activity in Marin County remained elevated during weeks 10 (March 6-12) and 11 (March 13-19), and increased in comparison to week 9, however, remained similar to week 8 activity.  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 13.2% during week 10 and 13.4% week 11.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza SeasonsInfluenza-like illness, Marin County, 2012-2015

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 

During week 10,  22 (22.0%) of the 100 specimens tested for influenza were positive.  Of the positive specimens from week 10, 18 (81.8%) were influenza A and 4 (18.2%) were influenza B. During week 11, 21 (20.8%) of the 101 specimens tested for influenza were positive.  Of the positive specimens from week 11, 16 (76.2%) were influenza A and 5 (23.8%) were influenza B.  During this influenza season through March 19, 165 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Season

PROVISIONAL DATA, SUBJECT TO CHANGE. 

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • Outpatient ILI activity and laboratory data indicate that influenza activity in California is still elevated, but is beginning to decrease.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was above expected levels for this time of year during weeks 10 (3.4%) and 11 (3.3%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 10, 25.8% (1,101 of 4,270 specimens tested) were positive for influenza.  Of these, 533 (48.4%) were positive for influenza A and 568 (51.6%) were positive for influenza B. Of the influenza A specimens, 66 (12.4%) were subtyped as 2009 A (H1), 14 (2.6%) were subtyped as seasonal A (H3), and 453 (85.0%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 11, 21.1% (885 of 4,186 specimens tested) were positive for influenza. Of these, 398 (45.0%) were positive for influenza A and 487 (55.0%) were positive for influenza B.  Of the influenza A specimens, 49 (12.3%) were subtyped as 2009 A (H1), 19 (4.8%) were subtyped as seasonal A (H3), and 330 (82.9%) were not subtyped.
  • The geographic spread of influenza activity in California remained widespread+ during week 11.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity decreased slightly, but remained elevated nationally.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 3.7% during week 10 and 3.2% during week 11, both above the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 23.1% (5,968 of 25,855 specimens tested) were positive for influenza during week 10 and 20.1% (4,816 of 23,946 specimens tested) were positive for influenza during week 11.
  • ​During week 10, the geographic spread of influenza activity was reported as widespread+ in 40 states, regional* in 10 states, and local^ in the District of Columbia. During week 11, the geographic spread of influenza activity was reported as widespread+ in 39 states, regional* in 10 states, and local^ in one state and the District of Columbia.  See map below for week 11.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap07.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.  https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2010%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2011%20-%20FINAL%20Report.pdf. Accessed 3/29/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 3/29/2016.

Marin

During weeks 8 (February 21-27) and 9 (February 28-March 5), influenza was still circulating in Marin County, however, there was a marked reduction in both influenza-like illness activity and the number of positive influenza tests during week 9 (Figure 2). 

Influenza-like illness activity 

Influenza-like illness activity in Marin County remained elevated during weeks 8 (February 21-27) and 9 (February 28-March 5), however, decreased in comparison to recent weeks.  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 13.6% during week 8 and 12.3% week 9.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza SeasonsInfluenza-like illness, Marin County, 2012-2015

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 

During week 8, 20 (23.0%) of the 87 specimens tested for influenza were positive.  Of the positive specimens from week 8, 10 (50.0%) were influenza A and 10 (50.0%) were influenza B. During week 9, 11 (12.8%) of the 86 specimens tested for influenza were positive.  Of the positive specimens from week 9, 7 (63.6%) were influenza A and 4 (36.4%) were influenza B.  During this influenza season through March 5, 122 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Season

PROVISIONAL DATA, SUBJECT TO CHANGE. 

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California remained widespreadduring week 9.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was above expected levels for this time of year during weeks 8 (3.8%) and 9 (3.8%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 8, 29.4% (1,602 of 5,453 specimens tested) were positive for influenza.  Of these, 730 (45.6%) were positive for influenza A and 872 (54.4%) were positive for influenza B. Of the influenza A specimens, 89 (12.2%) were subtyped as 2009 A (H1), 26 (3.6%) were subtyped as seasonal A (H3), and 615 (84.2%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 9, 29.3% (1,343 of 4,581 specimens tested) were positive for influenza. Of these, 635 (47.3%) were positive for influenza A and 708 (52.7%) were positive for influenza B.  Of the influenza A specimens, 52 (8.2%) were subtyped as 2009 A (H1), 17 (2.7%) were subtyped as seasonal A (H3), and 566 (89.1%) were not subtyped.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity remained elevated nationally.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 3.2% during week 8 and 3.5% during week 9, both above the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 17.6% (3,803 of 21,615 specimens tested) were positive for influenza during week 8 and 20.6% (4,918 of 23,910 specimens tested) were positive for influenza during week 9.
  • ​During week 8, the geographic spread of influenza activity was reported as widespread+ in 33 states, regional* in 14 states, local^ in one state and the District of Columbia, and sporadic~ in two states.  During week 9, the geographic spread of influenza activity was reported as widespread+ in 37 states, regional* in 13 states, and local^ in the District of Columbia.  See map below for week 9.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap07.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health. https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2008%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2009%20-%20FINAL%20Report.pdf. Accessed 3/14/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 3/14/2016.

Marin

During weeks 6 (February 7-13) and 7 (February 14-20), influenza activity increased in Marin County in comparison to recent weeks with elevated influenza-like illness activity (Figure 1) and an increase in the number of positive influenza tests (Figure 2). 

Influenza-like illness activity 

Influenza-like illness activity in Marin County was elevated during weeks 6 (February 7-13) and 7 (February 14-20).  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 14.3% during week 6 and 14.2% week 7.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza SeasonsInfluenza-like illness, Marin County, 2012-2015

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 

During week 6, 13 (13.5%) of the 96 specimens tested for influenza were positive.2  Of the positive specimens from week 6, 2 (15.4%) were influenza A and 11 (84.6%) were influenza B. During week 7, 18 (20.2%) of the 89 specimens tested for influenza were positive.  Of the positive specimens from week 7, 9 (50.0%) were influenza A and 9 (50.0%) were influenza B.  During this influenza season through February 20, 91 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Seasonlab_wks67.jpg

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

2All data have not been received for week 6. Data are preliminary and subject to change.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California remained widespreadduring week 7.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was above expected levels for this time of year during weeks 6 (4.1%) and 7 (4.0%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 6, 24.0% (1,248 of 5,200 specimens tested) were positive for influenza.  Of these, 619 (49.6%) were positive for influenza A and 629 (50.4%) were positive for influenza B. Of the influenza A specimens, 40 (6.5%) were subtyped as 2009 A (H1), 14 (2.3%) were subtyped as seasonal A (H3), and 565 (91.3%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 7, 31.8% (1,596 of 5,015 specimens tested) were positive for influenza. Of these, 767 (48.1%) were positive for influenza A and 829 (51.9%) were positive for influenza B.  Of the influenza A specimens, 75 (9.8%) were subtyped as 2009 A (H1), 23 (3.0%) were subtyped as seasonal A (H3), and 669 (87.2%) were not subtyped.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity increased from previous weeks.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 3.1% during week 6 and 3.2% during week 7, both above the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 12.0% (2,135 of 17,797 specimens tested) were positive for influenza during week 6 and 13.8% (2,599 of 18,844 specimens tested) were positive for influenza during week 7.
  • ​During week 6, the geographic spread of influenza activity was reported as widespread+ in 12 states, regional* in 20 states, local^ in 15 states and the District of Columbia, and sporadic~ in three states.  During week 7, the geographic spread of influenza activity was reported as widespread+ in 21 states, regional* in 18 states, local^ in 10 states and the District of Columbia, and sporadic~ in one state.  See map below for week 7.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap07.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.   https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2006%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2007%20-%20FINAL%20Report.pdf. Accessed 2/29/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 2/29/2016.

Marin

During weeks 4 (January 24-30) and 5 (January 31-February 6), influenza was circulating in Marin County with elevated influenza-like illness activity (Figure 1).  The number of positive influenza tests increased during week 5, leading to an increase in the percent positive (Figure 2). 

Influenza-like illness activity 

Influenza-like illness activity in Marin County was elevated during weeks 4 (January 24-30) and 5 (January 31-February 6).  Discharge data from Kaiser San Rafael, Marin General Hospital, and Novato Community Hospital emergency departments and visits to Sutter Terra Linda Urgent Care showed the percentage of visits associated with influenza-like illness (ILI) was 12.9% during week 4 and 13.0% week 5.  See Figure 1 below.

Figure 1: Proportion of Visits due to Influenza-Like Illness (ILI):  Kaiser San Rafael, MGH, and NCH Emergency Departments and Sutter Terra Linda Urgent Care, 2013-14, 2014-2015, and 2015-2016 Influenza SeasonsInfluenza-like illness, Marin County, 2012-2015

PROVISIONAL DATA, SUBJECT TO CHANGE. The case definition for ILI is any chief complaint that includes the following keywords or variants of the keywords: influenza, flu, influenza-like illness, pneumonia, fever, cough, and/or sore throat.

Influenza testing1 

During week 4, 7 (10.3%) of the 68 specimens tested for influenza were positive.  Of the positive specimens from week 4, 5 (71.4%) were influenza A and 2 (28.6%) were influenza B. During week 5, 13 (13.5%) of the 96 specimens tested for influenza were positive.  Of the positive specimens from week 5, 6 (46.2%) were influenza A and 7 (53.8%) were influenza B.  During this influenza season through February 6, 60 specimens have tested positive for influenza.  See Figure 2 below.

Figure 2.  Influenza Tests in Marin County, 2015-2016 Influenza Season
Influenza Tests in Marin County, 2014-2015

1 Laboratory results reported by Kaiser-Novato, Kaiser-San Rafael, Marin General Hospital, Novato Community Hospital, and Sutter Terra Linda Urgent Care.

Visit MarinFlu.org for influenza vaccination, testing, and treatment recommendations.

California

  • The geographic spread of influenza activity in California remained widespreadduring week 5.
  • Outpatient ILI activity as a percentage of total visits to sentinel providers was below expected levels for this time of year during weeks 4 (2.6%) and 5 (2.3%). 
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 4, 17.2% (536 of 3,120 specimens tested) were positive for influenza.  Of these, 271 (50.6%) were positive for influenza A and 265 (49.4%) were positive for influenza B. Of the influenza A specimens, 11 (4.1%) were subtyped as 2009 A (H1), 5 (1.8%) were subtyped as seasonal A (H3), and 255 (94.1%) were not subtyped.  
  • Of the specimens tested by the Respiratory Laboratory Network and Sentinel Laboratories during week 5, 20.6% (864 of 4,189 specimens tested) were positive for influenza. Of these, 442 (51.2%) were positive for influenza A and 422 (48.8%) were positive for influenza B.  Of the influenza A specimens, 38 (8.6%) were subtyped as 2009 A (H1), 12 (2.7%) were subtyped as seasonal A (H3), and 392 (88.7%) were not subtyped.
  • Visit the California Department of Public Health’s influenza surveillance website for more information.  

United States

  • Influenza activity increased slightly from previous weeks.   
  • The proportion of outpatient visits for influenza-like illness (ILI) was 2.2% during week 4 and 2.4% during week 5, both above the national baseline of 2.1%.
  • Of the specimens tested and reported by the U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 6.8% (1,085 of 15,964 specimens tested) were positive for influenza during week 4 and 9.1% (1,563 of 17,175 specimens tested) were positive for influenza during week 5.
  • ​During week 4, the geographic spread of influenza activity was reported as widespread+ in three states, regional* in 18 states, local^ in 16 states and the District of Columbia, and sporadic~ in 12 states.  No influenza activity was reported by one state.  During week 5, the geographic spread of influenza activity was reported as widespread+ in seven states, regional* in 17 states, local^ in 16 states, and sporadic~ in nine states and the District of Columbia. No influenza activity was reported by one state.  See map below for week 5.
  • For additional national influenza data, visit the Center for Disease Control and Prevention's influenza surveillance website.

usmap03.jpg

+Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
*Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions
^Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
~Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.

Additional flu trends can be seen in Google Flu Trends which uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States.  For more information and activity estimates from California, the U.S. and worldwide, see http://www.google.org/flutrends/

If you have any questions or comments please contact:
Haylea Hannah, MSPH
Epidemiology Fellow
(415) 473-6020
HHannah@marincounty.org

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

Sources

California Department of Public Health.  https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2004%20-%20FINAL%20Report.pdf and https://www.cdph.ca.gov/HealthInfo/discond/Documents/Week%2005%20-%20FINAL%20Report.pdf. Accessed 2/16/2016.

Centers for Disease Control and Prevention. https://www.cdc.gov/flu/weekly/. Accessed 2/16/2016.

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