National Covid-19 trends, January 2

Here are the latest national Covid-19 trends, according to the CDC and major wastewater surveillance providers:

• New hospital admissions with Covid-19 have increased 17%, from 3,600 admissions per day during the week ending December 16 to 4,200 admissions per day during the week ending December 23.
• Test positivity has increased 6%, from 12% of Covid-19 tests returning positive results during the week ending December 16 to 12.7% of positive tests during the week ending December 23.
• Healthcare visits for influenza-like illness have increased 17% between the week ending December 16 and the week ending December 23.
• SARS-CoV-2 concentration in wastewater has increased 21% between the week ending December 16 and the week ending December 23, and the national wastewater viral activity level is very high, per the CDC.
• SARS-CoV-2 concentration in wastewater has increased 21% between December 18 and December 25, per WastewaterSCAN.

This winter’s Covid-19 surge continues in the U.S. While data aren’t yet available for the weeks after Christmas and New Years, wastewater surveillance suggests there could be more SARS-CoV-2 going around right now than reported at this time last year — with variant JN.1 fueling the spread from holiday travel and gatherings.

Wastewater surveillance data from the three national dashboards (the CDC, WastewaterSCAN, and Biobot) all point to a major surge, with viral levels high and rising across the country. The CDC’s estimates suggest that SARS-CoV-2 levels in wastewater are currently higher than the peak of last winter’s surge, both nationally and for the four major regions. WastewaterSCAN’s dashboard also suggests higher coronavirus spread right now than this time last year; Biobot’s dashboard hasn’t yet been updated for the last week of December, but the available data show a significant acceleration.

For more information on where to find local wastewater data for your community and how to interpret the numbers, see my recent article in Scientific American. It’s important to note here that viral levels in wastewater don’t correspond perfectly to cases. The amount of coronavirus that a single sick person sheds in their sewage may vary based on their symptoms, how long they’re sick, which variant they were infected with, and other factors; at the population level, more factors (such as who is included in a sewershed) lead to variability. So I suggest taking any estimates of current case numbers with a grain of salt, though it is reasonable to guess that millions of Americans are getting infected each week right now.

Data from hospitals show that Covid-19 is leading to thousands of hospitalizations a day in the U.S. right now. The CDC’s surveillance shows that Covid-19’s burden on hospitals is much higher than the burdens from flu or RSV, though these two respiratory viruses are also causing a lot of disease right now. Some healthcare facilities are bringing back mask requirements as a result: for example, Los Angeles County reinstated mask mandates for these facilities at the end of December. (Better late than never?)

Omicron variant JN.1 is a major driver of new Covid-19 cases right now both in the U.S. and globally; see this week’s article about the variant for more details. JN.1 combined with the recent holidays and winter weather could give us a nasty January. As World Health Organization epidemiologist Maria Van Kerkhove shared on Twitter recently: the pandemic is not over; rather, it has entered a new phase “marked by complacency” from governments, health organizations, and leaders of all kinds.