That Uncertain Feeling - CDC Updates COVID Nowcast (8/29/25)

[Michael Coston]

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.


https://afludiary.blogspot.com/2025/08/that-uncertain-feeling.html
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[Michael Coston]

CDC Updates COVID Nowcast



#18,856

Earlier this week, in That Uncertain Feeling, I wrote that the CDC's COVID Nowcast webpage had not been updated since June 20th, and that it - and their wastewater surveillance page - both carried banners indicating `technical difficulties' were delaying data.

CDC Nowcast Screenshot (8/26/25)

Yesterday the CDC published a revamped COVID Nowcast, albeit on a different web url (https://www.cdc.gov/covid/php/variants/variants-and-genomic-surveillance.html), making it easy to miss.

This new version is (for now, at least) less detailed than the previous incarnation; it drops completely the HHS regional map (see above), and the number of variants being tracked has fallen from 19 (last June) to just 5 today.​

They have added a useful graphic showing the remarkable decline over time in the number of weekly COVID samples sequenced in the United States.


Those without a magnifying glass should know we've gone from a peak of > 90,000 sequences a week to averaging less than 300. A sampling size that makes it difficult to detect new variants until they've established a significant presence.


Based on extremely limited data, yesterday's update suggests that XFG is the only variant currently gaining ground, while the other four being tracked (NB.1.8.1, LP.8.1, NW.1, & LF.7) are either losing ground or holding steady.


After several weeks the CDC has removed the warning banners (see below) from their wastewater surveillance sites in yesterday's update.


But based on the map below, while there are still significant gaps in wastewater testing surveillance around the country, COVID levels are rising particularly in the south and west.



This chronic dearth of COVID data reflects a global shift in priorities - one that appears to prioritize economics and political expediencies over public health concerns - which has led to a dismantling of surveillance systems around the world (see From Here To Impunity).

As a result we are at increased risk of being blindsided by new COVID variants, an `antigenically shifted' seasonal flu virus, spillovers of H5N1, MERS-CoV, or something worse.​

There are increasing obstacles now in place for getting the COVID shot - even for seniors - that in the face of continually waning immunity, are only likely to exacerbate the impact of this fall's respiratory season.

While hopefully these COVID vaccine availability problem can be solved - until that happens I've still got my stash of KN95 face masks . . . .​

And unlike some people, I'm not afraid to use them.


https://afludiary.blogspot.com/2025/08/cdc-updates-covid-nowcast.html
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