That Uncertain Feeling

CDC Nowcast Screenshot (6/26/25)

#18,451

Sixty days ago (June 26th) we looked at the WHO's WHO TAG-VE Risk Assessment On COVID VUM (Variant Under Monitoring) XFG, which was released just a month after a similar WHO risk assessment on COVID VUM NB.1.8.1.

At that time, the most recent CDC COVID Nowcast (June 20th) estimated the prevalence of the top 3 COVID variants in the United States (see below) with a tremendous amount of uncertainty.

The CDC warned:

Due to low numbers of sequences being reported to CDC, precision in the most recent reporting period is low. CDC is moving to longer reporting periods to gather the number of sequences required to provide reliable nowcast estimates.

Since then, COVID activity across the United States has increased (see CDC report below), but the CDC's Nowcast hasn't been updated since June 20th.

The CDC's Wastewater surveillance system has been updating, but they also warn that due to unspecified `technical issues' wastewater data is currently delayed for COVID, Influenza, and RSV. 

What data they do have indicates that the XFG variant has become dominant in the United States (see below), but it isn't at all clear how current, or accurate, this information may be.

Hopefully these `technical issues' are temporary, and can be resolved before the fall/winter respiratory season begins, as it could affect many people's decision on whether (or when) to get the seasonal flu/COVID vaccines.  

This lack of good data isn't just limited to the United States, however, as 90% of the world's countries no longer reliably report COVID statistics to the WHO (see No News Is . . . Now Commonplace). 

We've seen similar reductions in reporting on novel influenza as well. 

Although public health organizations like the WHO and ECDC continue to promote increased surveillance (see ECDC: Updated Reporting Protocol for Zoonotic Influenza Virus) - for numerous and varied economic and political reasons - the sharing of data only seems to be getting worse (see From Here To Impunity).

This reduced surveillance and data sharing only increases the chances that we could be blindsided by a new COVID variant, an `antigenically shifted' seasonal flu virus, spillovers of H5N1, or something worse.

While we may get lucky - and nothing untoward happens this fall or winter - you can only cross a busy street blindfolded so many times before you get flattened.