County of Marin Health and Human Services

Influenza Surveillance Update - Week Ending February 1, 2020


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


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


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.


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.


California Department of Public Health. Accessed 2/4/20.

Centers for Disease Control and Prevention. Accessed 2/4/20.

Blog Category: