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 0.8 in every 100,000 people were hospitalized for COVID-19 during the week ending March 21.
- COVID-19 test positivity decreased significantly, from 2.8% of COVID-19 tests returning positive results during the week ending March 14 to 2.3% positive during the week ending March 21.
- SARS-CoV-2 concentration in wastewater decreased 24% between March 14 and March 21, and the national wastewater viral activity level is “very low,” per the CDC.
- SARS-CoV-2 concentration in wastewater decreased 10% between March 11 and March 18 and the national wastewater trend is “medium,” per WastewaterSCAN.
- Healthcare visits for influenza-like illness decreased 11% between the week ending March 14 and the week ending March 21, and this metric has gone below the level marking the end of flu season.
COVID-19 levels are relatively low across much of the U.S. as of late March — about as low as we generally see in plateaus between surges at this point in the pandemic, but still higher than what would be possible if widespread health precautions were still in place. Meanwhile, experts are monitoring a newer variant, BA.3.2, that will likely contribute to the next spike in cases.
Wastewater data from the CDC, WastewaterSCAN, and Biobot Analytics all report that SARS-CoV-2 levels in sewage are on the lower end. On the CDC’s map of wastewater viral activity levels by state, most states have “low” or “very low” SARS-CoV-2 levels, and the agency has updated its national activity level to “very low” as well. (The only states with moderate and high levels have limited testing sites, so their statewide averages could be skewed.)
I interpret the CDC’s “very low” category as, “as low as possible without collective precautions,” because the agency’s baseline for SARS-CoV-2 spread is regularly recalculated based on recent data and does not account for the true low levels we experienced early in the pandemic. WWSCAN, which has more longevity in its analysis, reports that recent national averages are below most plateaus we saw between surges in 2023-2025, but still several times higher than the true lows in 2021 and 2022.
COVID-19 test positivity, from the CDC’s lab surveillance network, is also the lowest it has been in a couple of years. While the agency revised the value for March 14 up slightly (from 2.53% to 2.77%) in this week’s update, its latest figure remains fairly low at 2.26%.
Test positivity, emergency department visits, and SARS-CoV-2 activity in wastewater are all at low or moderate plateaus across most regions. However, there are potential signals that this could change in the Northeast and South: WWSCAN reports possible upticks in these regions in its latest data. And the CDC’s infectious disease forecasting center reports that COVID-19 cases are “likely growing” in Massachusetts and Florida as of March 24, while they are “declining or likely declining” in 34 other states.
We are officially out of flu season, as the share of healthcare visits for flu-like illness has dropped below 3% in the CDC’s flu sentinel surveillance network. Other flu metrics, including test positivity, hospitalizations, and flu levels in wastewater, also continue to decline. RSV levels are still high, though, offering another reason to stay wary of airborne disease spread.
A variant called BA.3.2 will likely contribute to our next COVID-19 wave this summer as it grows from its currently-low levels in the U.S. In the week ending March 21, it made up about 11% of SARS-CoV-2 detections in wastewater, among the testing sites tracking variant data.
This strain isn’t actually new — it was first detected in fall 2024. But it’s continued circulating globally and is now outcompeting other variants, particularly in Europe over the winter, earning it the nickname “Cicada.” As BA.3.2 stems from an older Omicron lineage, our current vaccines may not work as well against it, adding to its capacity to reinfect people who were recently infected or vaccinated. Children may also be susceptible to this variant, variant tracker Ryan Hisner recently noted on Bluesky.
