Summary: Week of 8/5/24

We continue to monitor the evolving H5N1 influenza virus situation. As we do, a quick reminder that Biobot’s influenza A assay detects the H5N1 influenza subtype, which is an influenza A virus, but does not distinguish between the different subtypes of influenza A (e.g. H5N1 vs H1N1). 

Thankfully, we still have not seen large, widespread increases in influenza A concentrations. Data through week 31 (August 3) also indicate that influenza activity remains low in the four US regions. We want to highlight some important points about the role of Biobot’s wastewater data in understanding the current circulation/risk of H5N1: 

• At this point, we cannot determine if any upticks we’ve observed are due to seasonal influenza A virus or if H5N1 could have played a role. 
• Biobot is currently testing for influenza A in 9 out of the 13 states with positive dairy herds (Texas, New Mexico, Kansas, Idaho, Ohio, North Carolina, Iowa, Wyoming, and Oklahoma), among several other states across the country. 
• Our current assays do not distinguish between human infections and infected animals that are shed into the wastewater system. 

This situation is rapidly evolving and our team will continue to closely monitor H5N1. We will provide any additional information as it becomes relevant or available via Twitter and here in the risk reports.

Biobot’s national wastewater network showed very low national concentrations of influenza A & B and RSV during week 31, while SARS-CoV-2 concentrations continued to increase. While SARS-CoV-2 concentrations significantly increased in the South and Midwest, the rate of SARS-CoV-2 concentration increase appears to be slowing down in the Northeast and West, which is a welcome signal that activity could be slowing in those regions, although it’s still too early to tell. Nationally, major clinical metrics remained low for influenza and RSV in week 30, while metrics for COVID-19 remained elevated. 

The Bottom Line: COVID-19 activity remains elevated nationwide despite some signals that increases may be slowing down. Our recommendations to remain healthy are the same as in the winter: if you feel unwell, minimize contact with others, consider wearing a mask in crowded areas, and stay current with vaccinations and boosters.

National Outlook

RSV

Nationally, RSV concentrations remained very low in week 31. 

Influenza

Nationally, influenza A and B concentrations remained very low in week 31.  

Clinical data showed that the illness burden due to influenza remained quite low in week 30. The percentage of outpatient visits for influenza-like illness (ILI) – typical in flu, RSV, and COVID-19 patients – held steady and remains below the national baseline of 2.9%, currently at 1.5%. FluSurv-NET reports that the influenza hospitalization rate per 100,000 persons also remains very low, currently at 0.1 in week 30. These metrics remain at levels we would typically expect for this time of year and indicate low influenza activity.

COVID-19

Wastewater data show that COVID-19 activity and community viral load slightly increased during week 31 but continued to slow. It is still too early to tell how close we are to this summer’s peak. The national average SARS-CoV-2 wastewater concentration is now 670 copies per mL. 

Clinical COVID-19 metrics remain elevated. Test positivity continued to increase in week 30 at 16.3%, while COVID-NET reports that the national COVID-19 hospitalization rate slightly decreased, currently at 2.8 per 100,000 persons. Unfortunately, deaths due to COVID-19 increased in week 30 and currently represent 1.5% of all deaths in the US.

Regional

The South

RSV: In the South, RSV wastewater concentrations remained stable and very low during week 31.  

Influenza: Influenza A and B concentrations held steady at very low levels in the South during week 31. Clinical data continues to confirm that the disease burden due to influenza remains low—all Southern states remained in the minimal ILI activity level through week 30.  

COVID-19: SARS-CoV-2 wastewater concentrations significantly increased in the South during week 31, at 780 copies per mL. Georgia and Tennessee are the two Southern states in COVID-NET. While both states appear to have experienced decreases in the COVID-19 hospitalization rate in week 30, we’ve noticed that in recent weeks, the downward trends have been corrected and indicate that hospitalization rates remain elevated. It has been hard to tell in real time what the true hospitalization trends are in the South.

The Midwest

RSV: RSV concentrations remained stable and very low in the Midwest during week 31.  

Influenza: We have observed some fluctuations in influenza A concentrations in the Midwest over the past couple of weeks, and while we feel that this is most likely noise as concentrations remain low, we’ll be keeping an eye out. Influenza B concentrations remain consistently very low. Clinical data continues to show a low influenza illness burden in the Midwest—all states remained in the minimal ILI activity level in week 30. 

COVID-19: SARS-CoV-2 wastewater concentrations increased in the Midwest during week 31, at 753 copies per mL. Michigan, Minnesota, and Ohio are Midwestern states in COVID-NET. In week 30, the hospitalization rate increased in Michigan, decreased in Minnesota, and held steady in Ohio.

The Northeast

RSV: In the Northeast, RSV wastewater concentrations remained stable and very low during week 31.

Influenza: During week 31, Influenza A concentrations held steady and remained very low in the Northeast, while influenza B concentrations decreased. In week 30, all Northeastern states remained at the minimal ILI activity level. 

COVID-19: SARS-CoV-2 wastewater concentrations held steady in the Northeast during week 31, currently at 720 copies per mL. In week 30, hospitalization rates increased in New York, decreased in Maryland, and held steady in Connecticut. 

The West

RSV: RSV wastewater concentrations remained stable and very low in the West during week 31.  

Influenza: Influenza A and B concentrations held steady and remained very low in the West during week 31. During week 30, all Western states were at the Minimum ILI activity level. 

COVID-19: During week 31, SARS-CoV-2 wastewater concentrations slightly increased in the West, at 555 copies per mL. California, Colorado, New Mexico, Oregon, and Utah are Western states in COVID-NET. California has had a particularly intense COVID-19 surge this summer, and while hospitalization rates slightly increased during week 30, it still appears that the state is past its hospitalization peak for this surge. Hospitalization rates also increased in Oregon and declined in Colorado, New Mexico, and Utah. 

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Footnotes: 

Wastewater data from Biobot Analytics for RSV, influenza, and SARS-CoV-2 are through August 3, 2024 (MMWR week 31). Clinical data on testing, hospitalizations, and emergency department visits for RSV, influenza, and COVID-19 are from the Centers for Disease Control and Prevention. Updates to clinical data for RSV, influenza, and COVID-19 are through July 27, 2024 (MMWR week 30).