Summary: Week of 7/08/24

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 27 (July 6) 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 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 in the risk reports.

Biobot’s national wastewater network showed very low national influenza A & B and RSV concentrations during week 27, while SARS-CoV-2 concentrations continued to increase. Nationally, major clinical metrics remained low for influenza and RSV in week 26, while metrics for COVID-19 remained elevated. 

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, which thankfully does not currently 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 27. 

Influenza

Nationally, influenza A and B concentrations remained very low in week 27.  

Clinical data showed that the illness burden due to influenza remained quite low in week 26. 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 1.4%. FluSurv-NET reports that the influenza hospitalization rate per 100,000 persons also remains very low, currently at 0.1 in week 26. These metrics are 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 continued to increase during week 27. The national average SARS-CoV-2 wastewater concentration is now 470 copies per mL. 

Clinical metrics showed signs of increasing COVID-19 activity in week 26. Test positivity increased, currently at 9.0%. COVID-NET reports that the COVID-19 hospitalization rate also increased, currently at 1.7 per 100,000 persons. Deaths due to COVID-19 decreased in week 26 and currently represent 0.6% of all deaths in the US. 

Regional

The South

RSV: In the South, RSV wastewater concentrations remained stable and very low during week 27.  

Influenza: Influenza A and B concentrations held steady at very low levels in the South during week 27. 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 26.  

COVID-19: In good news, SARS-CoV-2 wastewater concentrations decreased in the South during week 27, currently at 353 copies per mL. The two Southern states in COVID-NET, an enhanced hospitalization surveillance system, are Georgia and Tennessee. Georgia experienced a decrease in the COVID-19 hospitalization rate in week 26, while the rate in Tennessee continued to increase. 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 27.  

Influenza: Influenza A and B wastewater concentrations remained stable and very low in the Midwest in week 27. Clinical data continues to show a low influenza illness burden in the Midwest—all states remained in the minimal ILI activity level in week 26. 

COVID-19: SARS-CoV-2 wastewater concentrations increased in the Midwest during week 27, at 394 copies per mL. Michigan, Minnesota, and Ohio are Midwestern states in COVID-NET. In week 26, hospitalization rates increased in Michigan and held steady in Minnesota and Ohio. Overall rates remained low in all three.  

The Northeast

RSV: In the Northeast, RSV wastewater concentrations remained stable and very low during week 27.

Influenza: Influenza A and B concentrations held steady and remained very low in the Northeast during week 27. In week 26, all Northeastern states remained in the Minimal ILI activity level. 

COVID-19: SARS-CoV-2 wastewater concentrations increased in the Northeast during week 27, at 646 copies per mL. Connecticut, Maryland, and New York are Northeastern states in COVID-NET. In week 26, hospitalization rates in all three remained steady and low.

The West

RSV: RSV wastewater concentrations remained stable and very low in the West during week 27.  

Influenza: Influenza A and B concentrations held steady and remained very low in the West during week 27. During week 26, all Western states were at the Minimum ILI activity level. 

COVID-19: During week 27, SARS-CoV-2 wastewater concentrations slightly increased in the West, currently at 359 copies per mL. California, Colorado, New Mexico, Oregon, and Utah are Western states in COVID-NET. Hospitalization rates increased in California, held steady in Colorado, and decreased in New Mexico, Oregon, and Utah in week 26. California continues to have the highest hospitalization rates of these Western states at 4.5 per 100,000 persons, similar to rates observed in California last November.

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Footnotes: 

Wastewater data from Biobot Analytics for RSV, influenza, and SARS-CoV-2 are through July 6, 2024 (MMWR week 27). 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 29, 2024 (MMWR week 26).