Nationwide WWSCAN Update 9/1/23

Hi everyone,

This newsletter contains updates on the WastewaterSCAN program with wastewater samples collected through August 29, 2023. Below you will find information on the program in terms of participating partners, review of targets being measured, as well as trends in concentrations of infectious disease targets.

Enjoy your weekend,

Ali & Marlene

WWSCAN Participant Stats:

• 179 plants sampling
• 42,571,760 people covered through sampling efforts
• 36 states represented
• 3 new onboarded sites - Grants Pass OR*, Lewis Auburn ME, and Wilson NC (*= new state)

The methods for our assays are in the public domain. You can access them using these QR codes:

During the August 2023 stakeholder meeting we announced we would be rolling out 5 new pathogen targets to all WWSCAN sites. The 5 new pathogens have undergone a rigorous validation process and are now ready to be deployed (see our process in the graphic below). You can read about the methods we are using to measure the new targets in these two preprints: first preprint, second preprint.

We plan to start prospectively measuring concentrations of the new targets next week; data will be available through a staged dashboard for about 2 weeks before the staged site will be launched for public consumption. We will email you with the exact date we will start early next week.

At last week's special stakeholder call we reviewed analysis being conducted to develop a clear way to communicate what wastewater is telling us about community disease circulation.

The new Wastewater Categories will use the following tools for interpretation:

• Levels tell us whether wastewater concentrations are relatively lower or higher
• Trends tell us how wastewater concentrations are changing
• Frequency of detection is important for rare targets

We will also use information about the start and end of wastewater events for seasonal pathogens using methodology described here. If you missed last week's call, here is the recording of the presentation. We plan to share more with you next Friday during our regularly scheduled monthly meeting.

SARS-CoV-2 N gene RNA concentrations (normalized by PMMoV) at most plants are rising. The median concentration across all sites over the last 21 days is 117,551 copies/gram (for reference median concentration in August 2023 was 44,036 copies/gram). Below are the SARS-CoV-2 N gene concentrations (normalized by PMMoV) from all participating WWSCAN sites across the country; raw data are shown as blue dots, the population weighted average is shown as a bold black line. Evident in the data are relatively high concentrations around the start of the year with medium levels presently observed.

Below are the SARS-CoV-2 N gene concentrations (normalized by PMMoV) from sites in the Midwest US (top left panel), Northeast US (top right panel), Southern US (bottom right panel) and Western US (bottom left panel). The population weighted average across the regional WWSCAN plants is shown in black, and the raw data are shown in blue.  Evident in the data is relatively high concentrations across all US regions around the start of the year with medium to high levels presently observed. It is important to note that concentrations across all 4 regionals levels are well above the detection limit of the N gene and appear to be rising across all 4 regions.

Below is the trend analysis for the SARS-CoV-2 RNA concentrations (N gene concentrations normalized by PMMoV) in wastewater solids at all participating plants. Red indicates a significant upward trend, blue is a significant downward trend, and dark grey is no trend. Yellow indicates that there were not enough data points to calculate a trend (we required 3 points over the last 21 days). You can read about our methods for trend analysis here. In short, we test for linear trends between log10-transformed concentration (target/PMMoV) and time; the trend must be classified as statistically significant (p<0.1).

Of the 179 sites: 23 show an upward trend, 142 show no trend, and 6 show a decreasing trend. The remaining 8 site (Fremont CA, Newark CA, Ontario CA, Petaluma CA, Union City CA, Louisville KY, Ithaca NY, and Sunnyvale TX) do not have enough data to calculate a trend.

The ratio of the XBB* mutations/N across all WWSCAN plants is shown in the chart below on the right. As the ratio reaches 100%, it suggests that all the SARS-CoV-2 genomes in wastewater have the XBB* mutations. These data indicate that the average ratio XBB* mutations/N is ~75% but some places show levels as high as 80-100%. This suggests the majority of infections across the communities are caused by XBB*. The chart on the left shows the ratio of the BA.5, BA.4, and BQ* mutation/N across all WWSCAN plants. It can be read the same way as the XBB* chart. The average ratio is about <10%. Note that our XBB* assay will also detect XBB.1.16, XBB.1.9,  FD.2 (XBB.1.5.15.2*), and EG.5. However the XBB* targets are NOT present in BA.2.86.

Influenza A (IAV) RNA concentrations (normalized by PMMoV) are very low. The median concentration across all sites over the last 21 days is below the lower detection limit of the assay. There have only been 141 positive samples out of 1,342 samples during the past 21 days (~10% detection rate). Below are the IAV RNA concentrations (normalized by PMMoV) from all participating WWSCAN sites across the country. The red dots are the raw data and the black line is the population weighted average.

Below are the IAV RNA concentrations (normalized by PMMoV) from sites in the Midwest US (top left panel), Northeast US (top right panel), Southern US (bottom right panel) and Western US (bottom left panel). The population weighted average across regional WWSCAN plants is shown in black, raw data are shown in red. Evident in the data is relatively high concentrations across all US regions around the start of the year with very low levels and mostly non-detects presently observed.

Below is the trend analysis for the IAV RNA concentrations (normalized by PMMoV) in wastewater solids at all participating plants. Red indicates a significant upward trend, blue is a significant downward trend, and dark grey is no trend. Yellow indicates that there were not enough data points to calculate a trend.

Of the 179 sites: 0 show an upward trend, 171 show no trend, and 0 show a decreasing trend. The remaining 8 site (Fremont CA, Newark CA, Ontario CA, Petaluma CA, Union City CA, Louisville KY, Ithaca NY, and Sunnyvale TX) do not have enough data to calculate a trend.

Influenza B (IBV) RNA concentrations are mostly non-detect at WWSCAN sites. There have only been 82 positive samples out of 1,341 samples during the past 21 days (~6% detection rate), all at low concentrations. Below is a heat map showing IBV detections at all the plants in WWSCAN in HHS Region 1. Each location is a row, and the date is a column. White indicates no sample, blue indicates non-detect, and the orange to red show variable concentrations if IBV. You can see how IBV RNA is occasionally detected since we began measuring it in mid December 2022 at these sites.

Respiratory syncytial virus (RSV) RSV RNA concentrations are generally low across the sites. The median concentration across all sites over the last 21 days is below the lower detection limit of the assay. There have only been 314 positive samples out of 1,342 samples during the past 21 days (~23% detection rate). Below are the RSV RNA concentrations (normalized by PMMoV) from all participating WWSCAN sites across the country. Raw data are shown as purple dots, and the black line is the population weighted average.

Below are the RSV RNA concentrations (normalized by PMMoV) from sites in the Midwest US (top left panel), Northeast US (top right panel), Southern US (bottom right panel) and Western US (bottom left panel). The population weighted average across regional WWSCAN plants is shown in black and raw data are shown as purple dots. Evident in the data is relatively high concentrations across all US regions around the start of the year with very low levels and mostly non-detects presently observed.

Below is the trend analysis for the RSV RNA concentrations (normalized by PMMoV) in wastewater solids at all participating plants. Red indicates a significant upward trend, blue is a significant downward trend, and dark grey is no trend. Yellow indicates that there were not enough data points to calculate a trend.

Of the 179 sites: 7 show an upward trend, 164 show no trend, and 0 show a decreasing trend. The remaining 8 site (Fremont CA, Newark CA, Ontario CA, Petaluma CA, Union City CA, Louisville KY, Ithaca NY, and Sunnyvale TX) do not have enough data to calculate a trend.

The 7 sites with an upward trend are clustered in the Bay Area of California and we will be watching these and the rest of the data closely to see if they might be signifying the onset of RSV wastewater events as described in this publication by our team. Last year, we saw RSV onset in wastewater occur as early as mid- to late-September in the Bay Area. We have also noted a higher rate of detection and concentration in the South recently, visible in the population weighted average line in the plot above. These changes are particularly apparent in Miami and Atlanta, among other locations in the South.

HMPV (human metapneumovirus) RNA concentrations are low. The median concentration across all sites over the last 21 days is below the lower detection limit of the assay. Below are the HMPV RNA concentrations (normalized by PMMoV) from all participating WWSCAN sites across the country. The turquoise dots are the raw data and the black line is the population weighted average.

Below are the HMPV RNA concentrations (normalized by PMMoV) from sites in the Midwest US (top left panel), Northeast US (top right panel), Southern US (bottom right panel) and Western US (bottom left panel). The population weighted average across regional WWSCAN plants is shown in black, and the raw data are shown as turquoise.  Evident in the data is relatively high concentrations across all US regions around the start of the year with very low levels and mostly non-detects presently observed.

Below is the trend analysis for the HMPV RNA concentrations (normalized by PMMoV) in wastewater solids at all participating plants. Red indicates a significant upward trend, blue is a significant downward trend, and dark grey is no trend. Yellow indicates that there were not enough data points to calculate a trend.

Of the 179 sites: 0 show an upward trend, 171 show no trend, and 0 show a decreasing trend. The remaining 8 site (Fremont CA, Newark CA, Ontario CA, Petaluma CA, Union City CA, Louisville KY, Ithaca NY, and Sunnyvale TX) do not have enough data to calculate a trend.

Norovirus GII (HuNoV GII) RNA  has been consistently detected at the sites. The median concentration across all sites over the last 21 days is 2,234,233 copies/gram. Below are the HuNoV GII RNA concentrations (normalized by PMMoV) from all participating WWSCAN sites across the country. The raw data are shown as green dots, and the population weighted average is shown as a black line.

Below are the HuNoV GII RNA concentrations (normalized by PMMoV) from sites in the Midwest US (top left panel), Northeast US (top right panel), Southern US (bottom right panel) and Western US (bottom left panel). The population weighted average across regional WWSCAN plants is shown in black, and raw data are green.

Below is the trend analysis for the Norovirus GII RNA concentrations (normalized by PMMoV) in wastewater solids at the plants. Red indicates a significant upward trend, blue is a significant downward trend, and dark grey is no trend. Yellow indicates that there were not enough data points to calculate a trend.

Of the 179 sites: 17 show an upward trend, 128 show no trend, and 26 show a decreasing trend. The remaining 8 site (Fremont CA, Newark CA, Ontario CA, Petaluma CA, Union City CA, Louisville KY, Ithaca NY, and Sunnyvale TX) do not have enough data to calculate a trend.

Mpox DNA We did not detect mpox DNA in samples from any site over the past three-weeks. The chart below shows every plant in WWSCAN (179) as rows, and the last 21 days as columns (labeled at the bottom axis). White indicates no samples, blue is non-detect for mpox DNA and red is detect for mpox DNA. As a reminder, you can access our paper in New England Journal of Medicine about how mpox wastewater monitoring compares to clinical reports of infectious here.

There are three recent papers related to this work that you might be interested in:

L. Roldan-Hernandez and A. B. Boehm. 2023. Adsorption of Respiratory Syncytial Virus, Rhinovirus, SARS-CoV-2, and F+ Bacteriophage MS2 RNA onto Wastewater Solids from Raw Wastewater. Environmental Science & Technology. Link.

A. B. Boehm, M. K. Wolfe, B. J. White, B. Hughes, D. Duong, A. Bidwell. 2023. More than a Tripledemic: Influenza A Virus, Respiratory Syncytial Virus, SARS-CoV-2, and Human Metapneumovirus in Wastewater during Winter 2022 - 2023. Environmental Science & Technology Letters, 10, 8, 622-627. Link.

A. B. Boehm, M. K. Wolfe, B. J. White, B. Hughes, D. Duong, N. Banaei, A. Bidwell. Human norovirus (HuNoV) GII RNA in wastewater solids at 145 United States wastewater treatment plants: Comparison to positivity rates of clinical specimens and modeled estimates of HuNoV GII shedders. Journal of Exposure Science and Environmental Epidemiology. Link.

At the September WWSCAN Stakeholder meeting we will discuss new targets being onboarded as well as new website features to help with interpreting wastewater trends and levels.

If you have questions about the website or anything else, submitting them in advance here will help us plan to address everything. We hope to see you there!