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:
- SARS-CoV-2 concentration in wastewater decreased 7% between September 16 and September 23, and the national wastewater trend is “high” (high concentration and no trend), per WastewaterSCAN.
- SARS-CoV-2 concentration in wastewater decreased 27% between September 19 and September 26, and the national wastewater viral activity level is “very low,” per the CDC.
- COVID-19 test positivity decreased 3%, from 5.0% of COVID-19 tests returning positive results during the week ending September 10 to 4.9% positive during the week ending September 26.
COVID-19 trends continue to diverge by region, as some parts of the country are seeing a summer wave taper off and others are seeing cases rise with the onset of colder weather. The Northwest seems to be the latest hotspot, and Western states overall are seeing an early start to flu season.
Cases continue to decline in the South, with wastewater data from the CDC, WastewaterSCAN, and Biobot Analytics as well as test positivity and emergency department visits all showing multiple weeks of decreases for this region. The CDC’s forecasting center, which uses ED data, estimates that COVID-19 cases are “declining” in Texas, Louisiana, and Florida, and “not changing” in other nearby states, as of September 30. However, COVID-19 levels are still higher in these states, as outbreaks from the summer wave have not yet concluded.
In the West, there seems to be a split between North and South: test positivity rates and ED visits are starting to decline in the Southwest but increasing in the Northwest. The test positivity rate for health region 10, which includes Alaska, Idaho, Oregon, and Washington, has been over 10% for the last three weeks. And the CDC’s forecasting center estimates cases are “declining or likely declining” in California, Nevada, Arizona, and Utah while they are “growing or likely growing” in Oregon, Idaho, Alaska, and Montana.
While the wastewater data providers all report decreases in their averages for the West, I suspect these could be biased by a higher concentration of testing sites in California compared to other nearby states. State-level data from the CDC show a clear decrease in SARS-CoV-2 levels at California’s 50+ testing sites in September, compared to increases at the smaller numbers of sites in Washington and Oregon. (Idaho and Alaska both have fewer than five sites with recent data.)
Flu cases are also starting to increase on the West coast. Test positivity data for flu, from the same CDC system where I find these data for COVID-19, show recent increases for both health region 10 and region 9, the Southwest. Epidemiologist Caitlin Rivers flagged this in her latest Outbreak Outlook newsletter, writing: “Both of these regions have low-but-rapidly-increasing emergency department visits for influenza, particularly in children.”
As I noted last week, I’m watching to see if COVID-19 levels go up further in the Northeast and Midwest, as these regions saw fewer cases this summer and often experience bigger outbreaks with colder weather. The CDC’s forecasting center estimates that cases are “growing or likely growing” in 14 states across these regions, though wastewater and testing data do not show much of a huge uptick yet.
There’s some good news for ongoing data availability this week: the CDC has awarded a new wastewater testing contract to Verily covering about 200 sites in the CDC National Wastewater Surveillance System network. As Verily also had the prior contract for these sites, there will be a shorter gap in data than if the CDC was switching to a different contractor. It’s still unclear how long we may see a reporting break, though — the latest note on the CDC NWSS dashboard simply says “there will be a brief gap.”
