Summary: Week of 7/29/24

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 30 (July 27) also indicate that influenza activity remains low in the four US regions. We want to highlight are 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 infections in humans 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 30, while the rate of SARS-CoV-2 concentration increase began to slow. The Northeast is the only region that experienced an increase in SARS-CoV-2 concentrations in week 30, with all other regions holding steady. These trends might signal that we are nearing the peak of the summer surge. Nationally, major clinical metrics remained low for influenza and RSV in week 29, while metrics for COVID-19 remained elevated.  

The Bottom Line: While the summer COVID-19 surge we are currently experiencing is showing some signs of slowing, viral activity remains elevated across the country. Our recommendations to remain healthy are the same as they were 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 30.

Influenza

Nationally, influenza A and B concentrations remained very low in week 30.  

Clinical data showed that the illness burden due to influenza remained quite low in week 29. 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 29. 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 30, but that the rate of increase has slowed. It is too early to tell if we are at or near the peak for this summer surge. The national average SARS-CoV-2 wastewater concentration is now 620 copies per mL. 

Clinical COVID-19 metrics remain elevated, but are also showing some hints that activity is slowing. While test positivity continued to increase in week 29, currently at 14.3%, COVID-NET reports that the national COVID-19 hospitalization rate decreased, currently at 1.8 per 100,000 persons. Unfortunately, deaths due to COVID-19 increased in week 29, and currently represent 1.1% of all deaths in the US.

Regional

The South

RSV: In the South, RSV wastewater concentrations remained stable and very low during week 30.   

Influenza: Influenza A and B concentrations held steady at very low levels in the South during week 30. Clinical data continues to confirm that disease burden due to influenza remains low – all Southern states remained in the Minimal ILI activity level through week 29. 

COVID-19: SARS-CoV-2 wastewater concentrations held steady in the South during week 30, currently at 564 copies per mL. Georgia and Tennessee are the two Southern states in COVID-NET. In good news, Georgia continued to experience a decrease in the COVID-19 hospitalization rate in week 29, while Tennessee held steady. Overall, the hospitalizations rates in both states are low.

The Midwest

RSV: RSV concentrations remained stable and very low in the Midwest during week 30. 

Influenza: Influenza A and B wastewater concentrations remained very low in the Midwest in week 30. Clinical data continues to show low influenza illness burden in the Midwest – all states remained in the Minimal ILI activity level in week 29.

COVID-19: SARS-CoV-2 wastewater concentrations held steady in the Midwest during week 30, currently at 694 copies per mL. Michigan, Minnesota, and Ohio are Midwestern states in COVID-NET. In week 29, the hospitalization rates in Minnesota decreased while rates in Michigan and Ohio held steady. Hospitalization rates remained low overall in these states.

The Northeast

RSV: In the Northeast, RSV wastewater concentrations remained stable and very low during week 30.

Influenza: Influenza A concentrations held steady and remained very low in the Northeast during week 30, while influenza B concentrations increased slightly. In week 29, all Northeastern states remained in the Minimal ILI activity level.

COVID-19: SARS-CoV-2 wastewater concentrations continued to increase in the Northeast during week 30, currently at 808 copies per mL. In week 29, the Northeastern states in COVID-NET, Connecticut, Maryland, and New York, all experienced decreases in COVID-19 hospitalization rates, which remained low overall.

The West

RSV: RSV wastewater concentrations remained stable and very low in the West during week 30. 

Influenza: Influenza A and B concentrations held steady and remained very low in the West during week 30. During week 29, all Western states were in the Minimal ILI activity level.

COVID-19: During week 30, SARS-CoV-2 wastewater concentrations held steady in the West, currently at 516 copies per mL. California, Colorado, New Mexico, Oregon, and Utah are Western states in COVID-NET. California finally experienced a big decline in hospitalization rates, which are now down from 5 per 100,000 persons in week 28 to 2.9 per 100,000 persons in week 29. Hospitalizations rates also decreased in Colorado and Oregon, and held steady in New Mexico and Utah in week 29.

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Footnotes: 

Wastewater data from Biobot Analytics for RSV, influenza, and SARS-CoV-2 are through July 27, 2024 (MMWR week 30). 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 20, 2024 (MMWR week 29).