National numbers, March 26

Data from WastewaterSCAN suggest that most sites in its network saw downward coronavirus trends or plateaus in recent weeks.

In the past week (March 16 through 22), the U.S. officially reported about 130,000 new COVID-19 cases, according to the CDC. This amounts to:

  • An average of 19,000 new cases each day
  • 41 total new cases for every 100,000 Americans
  • 13% fewer new cases than last week (March 9-15)

In the past week, the U.S. also reported about 17,000 new COVID-19 patients admitted to hospitals. This amounts to:

  • An average of 2,400 new admissions each day
  • 5.2 total admissions for every 100,000 Americans
  • 9% fewer new admissions than last week

Additionally, the U.S. reported:

  • 2,000 new COVID-19 deaths (300 per day)
  • 90% of new cases are caused by Omicron XBB.1.5; 3% by XBB.1.9.1; 2% by XBB.1.5.1; 0.4% by CH.1.1 (as of March 18)
  • An average of 40,000 vaccinations per day

Nationally, we continue to see the same slow decline of COVID-19 spread across the U.S., as shown by official case data, hospitalizations, and wastewater surveillance.

Reported cases dropped by 13% last week compared to the week prior, while new hospital admissions dropped by 9%. As I’ve noted in the last couple of updates, the CDC continues to deal with reporting delays from different state health departments. This week, Texas, Arkansas, Florida, and Indiana did not report cases to the CDC.

Wastewater surveillance data from Biobot and the WastewaterSCAN project suggest that COVID-19 levels are at slow declines or plateaus in most parts of the country, but some places may be seeing small increases. Biobot’s dashboard shows slight upticks in the Northeast, Midwest, and West coast regions, as of its March 22 update. 

Overall, Biobot’s data suggests that national coronavirus concentrations are lower than they’ve been in about a year—but still higher than we’ve seen at this point in 2021 and 2022. The low case numbers that health departments are putting out mask a high baseline of infections, in which many people are not getting PCR tests or reporting their cases to the healthcare system.

Data from the WastewaterSCAN project suggest that most of the project’s 148 monitoring sites reported downward trends or plateaus in coronavirus levels over the last three weeks. A few places have reported upticks, though, including sites in Kansas, Michigan, South Carolina, Massachusetts, and Oklahoma. 

One reason for these upticks could be XBB.1.9.1, the latest Omicron subvariant to draw concern among virologists. The CDC started reporting estimates for XBB.1.9.1 in its latest variant update (this Friday): the agency estimates that this variant caused 2.5% of new cases nationwide last week, with higher prevalence (about 13%) in the Midwest region that includes Iowa, Kansas, Missouri, and Nebraska.

XBB.1.9.1 is doubling “roughly every 8 days,” according to Marc Johnson, a virologist at the University of Missouri who leads the state’s wastewater surveillance program. Johnson predicts that this subvariant will be dominant in the U.S. by the end of April, but it could face competition from XBB.1.16—another descendant of XBB that has been spreading rapidly in India. 

Could the spread of these XBB sublineages across the U.S. cause a significant rise in cases and hospitalizations? It’s hard to say, given the complex picture of immunity in the country, with millions of people recently infected by a variety of variants. “Future waves are getting harder and harder to forecast,” Katelyn Jetelina wrote in Your Local Epidemiologist this week. Regardless, the same safety measures (masks, testing, etc.) continue to work against all new versions of the virus.

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