National Covid-19 trends, February 6

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

• New hospital admissions with Covid-19 have decreased 11%, from 3,600 admissions per day during the week ending January 20 to 3,200 admissions per day during the week ending January 27.
• Test positivity has decreased 42%, from 10.9% of Covid-19 tests returning positive results during the week ending January 20 to 6.3% of tests during the week ending January 27.
• Healthcare visits for influenza-like illness have decreased 3% between the week ending January 20 and the week ending January 27.
• SARS-CoV-2 concentration in wastewater has decreased 6% between the week ending January 20 and the week ending January 27, and the national wastewater viral activity level is high, per the CDC.
• SARS-CoV-2 concentration in wastewater has increased 9% between January 27 and February 3, per Biobot Analytics.
• SARS-CoV-2 concentration in wastewater has decreased 7% between January 22 and January 29, per WastewaterSCAN.

Continuing a trend from last week, wastewater surveillance data for the U.S. indicate that this winter’s Covid-19 surge may have gotten a second wind. National trends show slow declines or plateaus in SARS-CoV-2 transmission, while regional trends suggest transmission may be picking up again in the Northeast and South.

This week, the three national wastewater surveillance dashboards present three slightly different pictures, likely due to differences in update timing, data collection and analysis methods, and testing locations represented. The CDC’s dashboard represents the most testing sites, but are reported with the greatest delay and most likely to change with further updates. This dashboard currently shows a slowing decline in SARS-CoV-2 transmission at the national level, a steep increase in transmission for the South, and a slight increase in the Northeast.

Meanwhile, Biobot Analytics and WastewaterSCAN’s dashboards represent smaller numbers of testing sites, but are updated in closer to real time and with more consistency, as all sites in their networks are analyzed in the same way. Biobot’s dashboard shows a slight increase in coronavirus spread between January 27 and February 3, driven by an increase in the Northeast and plateaus in other regions. WastewaterSCAN’s dashboard shows a plateau, with relatively little change in transmission, across mid- to late-January, and messy recent trends at the regional and state levels (plateaus in some places, increases in others).

As trends from the healthcare system are typically a couple of weeks behind trends from wastewater data, the CDC’s hospitalization records continue to show declining Covid-19 admissions and emergency department visits. The CDC also reported a sharp decline in test positivity this week from its laboratory network, but I suspect that may be a data error or fluke considering the other metrics. The agency may revise this number up in its next update.

Variant estimates, also from the CDC, suggest that Omicron JN.1 is now causing more than 90% of new cases in the U.S. This variant has completely taken over, and is a clear culprit for this winter’s surge —- though holiday travel, indoor gatherings, and the complete lack of precautions in most spaces all played roles, too. Scientists are monitoring further new variants from the BA.2 family, such as BA.2.87, another variant that may have emerged from a chronic infection.

Meanwhile, flu activity is also rising in some parts of the country, per the CDC’s data. States in the Southeast and Midwest, as well as New York City and Washington, D.C., reported very high levels of influenza-like illness in the week ending January 27. While flu doesn’t lead to the same risks of severe or long-term illness as Covid-19, its spread is another good reason to keep masking up, avoiding crowded spaces, and taking other precautions during this time.