County of Marin Health and Human Services

Influenza Surveillance Update - Week Ending November 9, 2019


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


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


Visit for influenza vaccination, testing, and treatment recommendations.


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.


California Department of Public Health. Accessed 11/18/19.

Centers for Disease Control and Prevention. Accessed 11/18/19.


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