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 0.5 in every 100,000 people were hospitalized for COVID-19 during the week ending April 25.
- COVID-19 test positivity decreased slightly, from 1.4% of COVID-19 tests returning positive results during the week ending April 18 to 1.1% positive during the week ending April 25.
- SARS-CoV-2 concentration in wastewater decreased 9% between April 18 and April 25, and the national wastewater viral activity level is “very low,” per the CDC.
- SARS-CoV-2 concentration in wastewater decreased 16% between April 15 and April 22 and the national wastewater trend is “low,” per WastewaterSCAN.
A historic COVID-19 lull in the U.S. has continued through late April. Disease levels in wastewater and as measured by the healthcare system are at their lowest in several years; I’m surprised to see this considering the continued lack of widespread health measures. BA.3.2 (or “Cicada”) remains on the horizon but doesn’t appear to be having a widespread impact yet.
Both the CDC and WastewaterSCAN report lower levels of SARS-CoV-2 in wastewater and either plateaus or declines, both in their national averages and across all regions. The CDC reports slightly higher levels in the South than other regions, as well as “high” levels in Nebraska; but that state has only two testing sites with recent data, so this statewide average is likely skewed by an outbreak in one location. (Biobot Analytics has not posted an update this week.)
Recent national averages from WWSCAN are the lowest they’ve been since spring 2022, and are about two times the lows seen immediately after mass vaccination in spring 2021. But there are caveats to this comparison: WWSCAN’s testing network was more limited in 2021, and we don’t know how the virus’ continued evolution has impacted its shedding in sewage (as I discussed at The Sick Times’ webinar last week!).
Test positivity from the CDC’s network is also low and either declining or plateauing both nationally and for all regions. The latest national average, about 1.1%, is the lowest this metric has been since the CDC started tracking COVID-19 tests. And the CDC’s infectious disease forecasting center estimates that COVID-19 cases are “declining or likely declining” in 31 states as of April 28, and only “likely growing” in one state: Arizona.
BA.3.2, or “Cicada,” is likely still growing in prevalence according to sequences posted to the international repository GISAID. But it’s difficult to see in surveillance data, in part because the CDC has switched to a monthly update schedule for its variant estimates. Some variant experts on social media have posited that BA.3.2 may be underestimated in wastewater because it’s more prevalent among children — the youngest of whom may not show up in sewage because they wear diapers. Additional data will shed more light on this variant.
Meanwhile, a pathogen called hantavirus is in the news following a recent outbreak on a cruise ship. Scientists are currently investigating which species of hantavirus has infected passengers and how infections occurred; the virus typically spreads from contact with infected rodent waste, not person-to-person, but the latter is possible in rare cases. Journalist Kai Kupferschmidt wrote a helpful explainer of the situation in Science, describing how a cruise ship offers ideal conditions for a virus to spread through close contact. Like many pathogens, hantaviruses can also cause infection-associated chronic disease.
