BF.7, yet another Omicron subvariant of concern

BF.7 (shown here in light green) is among the Omicron subvariants starting to push out BA.5. Chart via the CDC.

Omicron BF.7, an offshoot of BA.5, is the latest subvariant to raise red flags among experts tracking COVID-19 in the U.S.

This week, BF.7 passed BA.2.75, another worrying lineage, in the CDC’s prevalence estimates: the CDC found that it caused about 2.3% of new cases nationwide in the week ending September 24. It’s most prevalent in the Northeast right now: in New England, it caused almost 4% of new cases last week, the CDC estimates.

BF.7 has an additional spike protein mutation compared to BA.5, CDC spokesperson Jasmine Reed told CBS News last week. The agency is concerned that this “genetic change” could lead to Evusheld, an antibody drug used by immunocompromised people, becoming less effective. It could also contribute to a new wave of reinfections, as we’ve seen with other Omicron subvariants in the last few months.

Here’s a quote from Dr. Stuart Ray, a data expert at John Hopkins’ Department of Medicine, in a Fortune article about BF.7:

“The same growth advantage in multiple countries makes it reasonable to think that BF.7 is gaining a foothold,” and that it’s potentially more transmissible than parent BA.5, Ray said. Children of variants “don’t grow relative to their parent unless they have an advantage.”

We have relatively little data on BF.7 so far, but it’s worth monitoring closely in the coming weeks.

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