Sunday, January 8, 2023

Quick update on where we are with newest Covid-19 variant XBB.1.5

The newest Covid variant might be an American native version of the pandemic virus.

At least it was most widespread earliest in New England. 

Omicron XBB.1.5 was first identified in New York and Massachusetts, and is now rampaging across the country. It is still comparatively rare in the rest of the world.

As of the end of last week in the U.S., it represented three quarters of Covid-19 cases in the northeast, and nearly a third of cases nationwide. It has been identified in Hawai'i, but not yet in significant numbers. 

"XBB.1.5 has not been detected in clinical samples across the state but was found in Honolulu County wastewater," reported the Hawai'i State Department of Health in its Wastewater Surveillance Report of January 3, 2023.

It seems to be more transmissible than earlier versions, but it is not yet clear whether it makes you sicker or less sick. One report suggests that it is “displaying slightly weaker immune evasion capability than XBB.1.”

That’s not necessarily great news, because an Australian study found that XBB.1 was “highly immune-evasive.” 

Best guess is that the vaccines and boosters will continue to have value, particularly the most recent bivalent booster vaccine. But they might not provide as robust protection as they do against older version for which they were designed. 

And for those who become seriously ill, at least some of the antivirals, like Paxlovid, continue to be effective against XBB.1.5. Others, like Evusheld, may not be as effective. 

It should be noted that researchers in some of these cited studies, in the interest of fast-changing public health threats, have released preliminary versions of their papers. So some of the work has not yet gone through the full peer review process.

© Jan TenBruggencate 2023

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