Summary: Week of 7/01/24

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 26 (June 29) 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 8 out of the 12 states with positive dairy herds (Texas, New Mexico, Kansas, Idaho, Ohio, North Carolina, Iowa, and Wyoming), among several other states across the country. 
• Our current assays do not distinguish between human infections and infected animals that shed into the wastewater system. 

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

Biobot’s national wastewater network showed very low national influenza A & B and RSV concentrations during week 26, while SARS-CoV-2 concentrations increased. Nationally, major clinical metrics remained low for influenza and RSV in week 25, while metrics for COVID-19 remained elevated. The percentage of outpatient visits due to influenza-like illness (ILI) remains below the national baseline of 2.9%, currently at 1.5%. All states have a minimal ILI activity level; overall, the clinical respiratory illness burden remains low. 

The Bottom Line: During the summer months, we are continuing to keep our eyes on two things: 1. Increasing SARS-CoV-2 concentrations indicative of a summer wave, similar to what we saw last August, and 2. The evolving H5N1 situation does not pose a significant threat to human health. Closely monitoring both these situations is essential to protecting human health. Our recommendations to keep yourself and loved ones healthy remain the same: 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 26. 

Influenza

Nationally, influenza A and B concentrations remained very low in week 26.  

Clinical data showed that the illness burden due to influenza remained quite low in week 25. 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 0.2 in week 25. These metrics are at levels we would typically expect for this time of year and indicate low influenza activity.

COVID-19

Wastewater data show COVID-19 activity and community viral load increased during week 26. The national average SARS-CoV-2 wastewater concentration is now 446 copies per mL. 

Clinical metrics showed signs of increasing COVID-19 activity in week 25. Test positivity increased, currently at 8.1%. COVID-NET reports that the COVID-19 hospitalization rate held steady, currently at 1.4 per 100,000 persons in week 25. Deaths due to COVID-19 increased in week 15 and currently represent 0.8% of all deaths in the US.

Regional

The South

RSV: In the South, RSV wastewater concentrations remained stable and very low during week 26.  

Influenza: Influenza A and B concentrations held steady at very low levels in the South during week 26. Clinical data continues to confirm that the disease burden due to influenza remains low—all Southern states remained at a minimal ILI activity level through week 25.  

COVID-19: SARS-CoV-2 wastewater concentrations significantly increased in the South during week 26, at 433 copies per mL. Georgia and Tennessee are the two Southern states in COVID-NET, an enhanced hospitalization surveillance system. Georgia’s COVID-19 hospitalization rate decreased in week 25, while Tennessee’s increased. Overall, COVID-19 hospitalization rates in both states remained low.

The Midwest

RSV: RSV concentrations remained stable and very low in the Midwest during week 26.  

Influenza: Influenza A and B wastewater concentrations remained stable and very low in the Midwest in week 26. Clinical data shows a low influenza illness burden in the Midwest—all states remained in the minimal ILI activity level in week 25. 

COVID-19: SARS-CoV-2 wastewater concentrations slightly decreased in the Midwest during week 26, at 299 copies per mL. Michigan, Minnesota, and Ohio are Midwestern states in COVID-NET. In week 25, hospitalization rates held steady in Michigan, decreased in Minnesota, and slightly increased in Ohio, but overall rates remained low in all three.

The Northeast

RSV: In the Northeast, RSV wastewater concentrations remained stable and very low during week 26.

Influenza: Influenza A and B concentrations held steady and remained very low in the Northeast during week 26. In week 25, all Northeastern states remained in the Minimal ILI activity level. 

COVID-19: SARS-CoV-2 wastewater concentrations significantly increased in the Northeast during week 26, at 548 copies per mL. Connecticut, Maryland, and New York are Northeastern states in COVID-NET. In week 25, hospitalization rates in all three held steady and remained low.

The West

RSV: RSV wastewater concentrations remained stable and very low in the West during week 26.  

Influenza: Influenza A and B concentrations held steady and remained very low in the West during week 26. During week 25, all Western states were at the Minimum ILI activity level. 

COVID-19: During week 26, SARS-CoV-2 wastewater concentrations increased in the West at 355 copies per mL. California, Colorado, New Mexico, Oregon, and Utah are Western states in COVID-NET. Hospitalization rates held steady in California, New Mexico, and Utah in week 25, while rates in Colorado and Oregon decreased. California continues to have the highest hospitalization rates of these Western states at 3.8 per 100,000 persons, similar to rates observed in California last October.

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Footnotes: 

Wastewater data from Biobot Analytics for RSV, influenza, and SARS-CoV-2 are through June 22, 2024 (MMWR week 25). 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 June 15, 2024 (MMWR week 24).