Modified vaccines less effective against new variants, 2 studies show

Two studies have found the omicron booster to be lacking when it comes to its strength against new COVID-19 subvariants BQ.1.1, XBB and BA.2.75.2 — which, together, account for 38 percent of cases. 

With the updated, BA.4/5-focused boosters, researchers at the Galveston-based University of Texas Medical Branch found that antibodies were about four times lower against BQ.1.1 compared to BA.5, according to a small study published Dec. 6 in Nature. Against XBB.1, antibodies were eight times lower among the 29 analyzed blood samples. 

A different study published the same day in The Lancet, which tracked the vaccine's effectiveness versus XBB sublineages, found similar results. Both studies were small, as they analyzed about 30 samples each, but they offer the first glimpse at how the bivalent boosters authorized in early fall act against new variants. 

BQ.1.1 is the leading subvariant with 31.9 percent of infections, and XBB and BA.2.75.2 follow behind with 5.5 percent and 0.5 percent, according to CDC data. Subvariant XBB.1 is not tracked by the CDC. 


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