SCAN Update - 1/8/25

This blog post describes data collected at 8 wastewater treatment plants in the Greater Bay Area of San Francisco, CA, including Sacramento, that are partners in the SCAN project which began in late 2020. The SCAN plants are a subset of the WastewaterSCAN plants.

‌All samples picked up by the couriers as of 1/7/25 have been processed and their data are on the site: data.wastewaterscan.org. For site level summaries of the SCAN plants with current Wastewater Categories and concentration plots, see the following links:

• Gilroy
• Oceanside SF
• Palo Alto
• Sacramento
• San Jose
• Southeast SF
• Sunnyvale
• SVCW

SARS-CoV-2 N gene concentrations were between ND - 1,083,00 copies per gram over the last 3 weeks. Below are the current SARS-CoV-2 wastewater categories for the SCAN sites (recall the category is determined by both the trend and the level):

• Gilroy, Palo Alto, Sacramento, San Jose, and Southeast SF are in the LOW Wastewater Category for SARS-CoV-2
• Oceanside SF, SVCW and Sunnyvale are in the MEDIUM Wastewater Category for SARS-CoV-2

Below are all the data from all the SCAN plants for the last two years. You can access the graph here. The population weighted average across the SCAN plants is shown in black. The population weighted average is slowly rising but concentrations are significantly lower than where they were this time last year (Jan 2024).

Below are plots from Oceanside SF, Sacramento, San Jose, and Southeast SF showing the relative proportions of different variants inferred from sequencing the entire genome of SARS-CoV-2. White and grey striped bars indicate no data is currently available for that week.

Note that the sequencing data are always from samples taken between 1-2 weeks ago (in this case, Dec 28, 2024). In the most recent samples, KP.2 made up the largest proportion of lineages detected at Sacramento (31.9%, KP.3 made up the largest proportion of lineages detected at San Jose (88.2%) and Oceanside SF (50%), and JN. 1.1.16 made up the largest proportion of lineages detected Southeast SF (56.9%).

Influenza A (IAV) RNA was detected in 99% of samples in the past 3 weeks. Below are all the IAV data from all the SCAN plants for the last two years. You can access the graph here. The population weighted average across the SCAN plants is shown in black.

All 8 sites in the SCAN network (Gilroy, Oceanside SF, Palo Alto, Sacramento, San Jose, Southeast SF, SVCW, and Sunnyvale) have tested positive for the H1 marker in Influenza A since the H1 marker assay resumed last week.

All 8 sites in the SCAN network (Gilroy, Oceanside SF, Palo Alto, Sacramento, San Jose, Southeast SF, SVCW, and Sunnyvale) have tested positive for the H3 marker in influenza A since we began testing for the marker prospectively in mid July 2024. We started seeing consistent positive detections of the H3 marker in Dec 2024.

All 8 sites in the SCAN network (Gilroy, Oceanside SF, Palo Alto, Sacramento, San Jose, Southeast SF, SVCW, and Sunnyvale) have tested positive for the H5 marker in influenza A since we began testing for the marker prospectively in May 2024.

Influenza B (IBV) RNA has regularly been detected in samples collected from SCAN sites in the last 3 weeks. In the chart below (representing data from the past 1 year), the population weighted average across the SCAN plants is shown in black. You can access the graph here.

Below are the current IBV wastewater categories for the SCAN sites (recall the category is determined by both the trend and the level):

• Gilroy, Oceanside SF, Palo Alto, Sacramento, Southeast SF, and SVCW are in the LOW Wastewater Category due to not being in seasonal onset for IBV
• Sunnyvale is in seasonal onset and in the MEDIUM Wastewater Category for IBV
• San Jose is in seasonal onset and in the HIGH Wastewater Category for IBV

RSV RNA was detected in ~98% of samples in the past 3 weeks. The median RSV RNA concentration across all SCAN sites in the last 3 weeks was 51,455 copies per gram. Currently 7 out of 8 SCAN sites have hit the threshold for seasonal onset for RSV in wastewater.

In the chart below (representing data from the past 2 years), the population weighted average line across all the SCAN sites is shown in black, and you can see the current concentrations relative to the peak RSV levels from late last year. The link to the chart below is here if you would like to interact with it.

Below are the current RSV wastewater categories for the SCAN sites (recall the category is determined by both the trend and the level):

• Southeast SF is in the LOW Wastewater Category due to not being in seasonal onset for RSV
• Gilroy, Oceanside SF, Palo Alto, Sacramento, San Jose, SVCW and Sunnyvale are in seasonal onset and in the HIGH Wastewater Category for RSV

‌HMPV (Human metapneumovirus) RNA was detected in ~83% of samples in past 3 weeks. The median HMPV RNA concentration across all SCAN sites in the last 3 weeks was 6,109 copies per gram. Below are the current wastewater categories for the SCAN sites (recall the category is determined by both the trend and the level):

• Gilroy, Palo Alto, Sacramento, Southeast SF, and SVCW are in the LOW Wastewater Category due to not being in seasonal onset for HMPV
• Oceanside SF, San Jose, and Sunnyvale are in seasonal onset and in the HIGH Wastewater Category for HMPV

In the chart below, the population weighted average line across all the SCAN plants is shown in black (link here to this chart if you want to interact with it) since we started monitoring HMPV at SCAN sites. Evident in the chart are the very low HMPV concentrations across all SCAN sites.

EV-D68 RNA was detected in 92% of samples collected at all SCAN sites in the last 3 weeks.

Below are the current wastewater categories for the SCAN sites (the category is determined by the frequency of detection):

• Southeast SF is no longer in seasonal onset and in the LOW Wastewater Category for EV-D68
• Gilroy, Oceanside SF, Palo Alto, Sacramento, San Jose, SVCW and Sunnyvale are in the HIGH Wastewater Category for EV-D68

In the chart below, the population weighted average line across all the SCAN plants is shown in black over the last 12 months. Evident in the chart were increasing EV-D68 concentrations in early August 2024, concentrations plateauing in early November 2024 to late December 2024 before beginning to rise again at the start of 2025.

Norovirus GII RNA was detected in 100% of samples from SCAN sites over the last 3 weeks, which is what we are observing across the national WWSCAN sites as well. In the chart below, the population weighted average line across all the SCAN plants is shown in black. Norovirus concentrations remain elevated across all SCAN sites and are still higher than they were this time last year. Current Norovirus concentrations are some of the highest we've seen at SCAN sites since we began monitoring in December 2022.

Below are the current Norovirus wastewater categories for the SCAN sites (recall the category is determined by both the trend and the level):

• San Jose and Sunnyvale are in the MEDIUM Wastewater Category for Norovirus
• Gilroy, Oceanside SF, Palo Alto, Sacramento, Southeast SF and SVCW are in the HIGH Wastewater Category for Norovirus

The plot below shows the Norovirus concentrations at the SCAN sites since we began monitoring in late 2022. The population weighted average line is shown in black. You can interact with the chart of all the plants at this link.

Mpox clade II DNA was not been detected at any SCAN sites in the last 3 weeks. Currently all SCAN sites are in the 'LOW' category for Mpox clade II.

The heat map below shows all the SCAN sites as a row, and each date as a column since July 2022. The color blue means that Mpox clade II DNA was not detected in the sample, and the dark red color means it was detected. White indicates no sample was collected. The chart shows all the data we have collected. You can access the chart here.

Candida auris DNA was detected at 5 SCAN sites in the last 3 weeks (San Jose and Sunnyvale). Currently 7 SCAN sites are in the 'LOW' category for C. auris and Oceanside SF is in the 'MEDIUM' category for C. auris.

The heat map below shows all the SCAN sites as a row, and each date as a column for all data collected since monitoring began in July 2023. The color blue means that Candida auris DNA was not detected in the sample, and the dark red color means it was detected. White indicates no sample was collected. You can access the chart here.

Hepatitis A RNA was detected at 4 of the SCAN sites (Sacramento, San Jose, SVCW and Sunnyvale) in the last 3 weeks.

• Gilroy, Oceanside SF, Palo Alto, Sacramento, Southeast SF, Sunnyvale and SVCW are in the LOW Wastewater Category for Hepatitis A
• San Jose is in the MEDIUM Wastewater Category for Hepatitis A

The heat map below shows all the SCAN sites as a row, and each date as a column for all data collected since monitoring began in July 2023. The color blue means that Hepatitis A RNA was not detected in the sample, and the dark purple color means it was detected. White indicates no sample was collected. You can access the chart here.‌

Please email Amanda Bidwell (albidwel@stanford.edu) if you do not have the calendar invite for the WWSCAN partner call.