COVID-19, Influenza, and RSV Data

 Wastewater  Test Positivity  Vaccination  Additional Data  FAQs   

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Wastewater monitoring of viruses is a meaningful way to show community-level infection trends over time. Several watershed sites in SLO County now perform wastewater monitoring of SARS-CoV-2 (the virus that causes COVID-19), influenza, and RSV. The charts below show both the raw viral detections (points) and the calculated smoothed averages (lines). Raw data points show viral detections but are inherently volatile and may reflect anomalies. Smoothed averages reduce day-to-day variability and improve accuracy. Data is presented separately for each site, as wastewater analysis is performed by different laboratories and includes multiple pathogens. We are grateful to these sites for their work and partnership in understanding respiratory virus trends in SLO County. Wastewater data is typically updated weekly on Fridays; however, individual sites may experience occasional reporting delays. Learn more about how wastewater monitoring works.


Test Positivity 

Test positivity shows the number of positive results divided by the total number of tests performed for each virus. Test positivity only takes into account PCR or professional antigen tests; at-home tests are not included. Though test positivity does not document the true burden of disease within a community, it can be helpful in showing general trends when used together with other data sources such as wastewater. This data is updated weekly.



Vaccination numbers reported here reflect the number of SLO County residents who received at least one vaccine dose during and immediately before the respiratory virus season (the timeframe of September through April) of the years noted. These numbers will differ from other counts that do not use the same timeframe. The percentages shown here reflect total SLO County population rather than eligible population. This data is updated monthly. Detailed data for COVID-19 vaccination is also available from the California Department of Public Health.


2023-2447,446 (17%)
2022-2363,282 (23%)
2021-22143,419 (51%)
2020-21141,408 (51%)



2023-2475,530 (27%)
2022-2378,942 (28%)
2021-2279,799 (29%)
2020-2173,479 (27%)
2019-2076,319 (28%)




Additional Data: Hospitalizations, Deaths, Variants

Find data on COVID-19 hospitalizations, ER visits, deaths, variants and more via the links below.

icon-CDPH-dashboard-wide.pngCDPH Respiratory Virus Dashboard
CDC COVID Data Tracker

Variants (CDC)

Previous Dashboards

To see an archive of our previous dashboards, please use the links below.

See previous dashboard: Sept 2022 - Mar 2024

See previous dashboard: Mar 2020 - Sept 2022



How often is this dashboard updated?

Most graphs on this dashboard are updated weekly on Fridays. Vaccine data is updated monthly. Some wastewater surveillance sites may have weeks when they are unable to report, and there may be weeks when data is not available for all sections.


Why does this dashboard now include data for flu and RSV as well as COVID-19? 

This updated and expanded dashboard now highlights three common respiratory diseases that we have the ability to monitor regularly: COVID-19, influenza, and RSV. While we have provided COVID-19 data for some time, a national wastewater program has allowed us to expand this data to include other common respiratory viruses as well. This data provides a more comprehensive view of local respiratory virus activity. Together, these diseases strain our healthcare systems and create both short-term burdens (such as missed work and school) and severe health challenges for individuals and families. This data can help us better understand these pathogens by documenting their trends and impact on the community.

How does wastewater testing work?

Environmental monitoring of wastewater is an important tool in understanding the total impact of specific viruses in our community. In SLO County, we are fortunate to have multiple watershed sites currently performing wastewater monitoring at regular intervals. Technicians gather samples from a wastewater treatment facility and the samples are then analyzed in a lab to determine the concentration of virus present. Samples are representative of the area served by the particular treatment plant. Samples may reflect infections among people who have symptoms as well as those who do not have symptoms or are just developing early, mild symptoms and have not yet tested. 

While wastewater cannot detect the number of people who are currently infected with a virus, it is an indicator of changes in community-level transmission. This means that wastewater testing can be used to detect general trends: whether the detectable amount of virus in a sampling zone is going up, going down, or staying about the same.

While wastewater monitoring for disease presence is not a new method (it has been used for nearly 70 years) it is newer to SLO County. Amongst many other advantages, wastewater monitoring is unbiased, non-invasive, inclusive, inexpensive, and provides insights into changes in community-level infection.  Find more information about wastewater monitoring from the California Department of Public Health.

Contact Us

We are working hard to provide relevant and meaningful information on COVID-19 and other respiratory viruses in SLO County, and we welcome feedback and questions. While we do not have the capacity to provide data in response to each individual request, we appreciate the input and will update the information we provide as resources allow. If you have questions or comments about the data displayed, please contact us.