Here are the latest national COVID-19 trends, according to the U.S. Centers for Disease Control and Prevention (CDC) and major wastewater surveillance providers:
- About 0.2 in every 100,000 people were hospitalized for COVID-19 during the week ending May 23.
- COVID-19 test positivity stayed consistent, with 0.8% of COVID-19 tests returning positive results during the week ending May 16 and 0.79% positive during the week ending May 23.
- SARS-CoV-2 concentration in wastewater stayed consistent between May 16 and May 23, and the national wastewater viral activity level is “very low,” per the CDC.
- SARS-CoV-2 concentration in wastewater decreased 21% between May 13 and May 20 and the national wastewater trend is “low,” per WastewaterSCAN.
A record-breaking COVID-19 lull has continued in the U.S. through late May. The latest national estimates for SARS-CoV-2 spread are the lowest they have been since spring 2021. While there are signs of possible case increases in some locations, these are preliminary and difficult to interpret.
The CDC, WastewaterSCAN, and Biobot Analytics report very low national and regional averages of SARS-CoV-2 in U.S. wastewater. This is also true for state and local wastewater surveillance programs, such as those in California, New York, and Illinois. In Boston, where wastewater surveillance has been consistent since spring 2020 (as Biobot is based there), recent samples have even included some nondetections, meaning levels of SARS-CoV-2 are too low for Biobot’s testing to pick up — the last time this happened was July 2021.
Healthcare system metrics also continue to report very low levels. COVID-19 test positivity from the CDC’s laboratory testing network remains under 1% nationally and for almost all health regions. And the agency’s infectious disease forecasting center (which uses emergency department data) estimates that cases are “declining or likely declining” in 12 states and “not changing” in 16 states, as of May 26.
Last week, I flagged that there were signals of potential COVID-19 increases in the South, based on test positivity and the CDC’s modeled estimates. This week, however, those signals are less strong; test positivity is trending back down in health region 3 and the modeling center estimates that cases are only “likely growing” in one Southern state, Texas.
There are now signs of potential increases in other regions. Biobot notes a potential slight increase in SARS-CoV-2 levels in wastewater in the Midwest, while WWSCAN notes one in the Northeast. The CDC also estimates cases are “likely growing” in Connecticut. And CDC test positivity data report potential increases in the Great Plains and Southwest (health regions 7 and 9).
But these are all preliminary data, like the trends in the South last week. I typically wait to see at least two weeks of a trend before confidently saying that COVID-19 cases are increasing in a particular region or location.
When comparing recent wastewater measurements to historical ones, I often note that SARS-CoV-2 levels in sewage are an imperfect predictor of actual infections in the community. A recent scientific paper in Science from Syracuse University researchers proposes a new method for estimating infections: using the genetic diversity present in viral samples (or, roughly, the number of variants) rather than concentration. If replicated by other research, this method could be used for other viruses along with SARS-CoV-2, the authors said.
Along with COVID-19, levels of most other common viruses, such as flu and RSV, are lower right now. But one exception is norovirus, which causes nasty gastrointestinal symptoms; it’s made headlines recently with an outbreak among hikers in California. Another GI pathogen called rotavirus and the respiratory pathogens rhinovirus and enterovirus are also spreading at higher levels, according to wastewater and test positivity data.
