Four vaccine doses provide low neutralization against BQ.1.1 and XBB.1, study suggests
San Francisco Chronicle, November 4, 2022
Newer omicron COVID-19 subvariants such as BQ.1.1 and XBB.1 have accumulated additional spike mutations that impact the efficacy of available vaccines, according to a pre-print study published Thursday by University of Texas Medical Branch. Researchers collected three human serum panels from individuals 1-3 months after their fourth dose of the original formula mRNA vaccine or one month after a bivalent booster dose. What they found is that while the updated bivalent booster elicits better neutralization against the newly emergent omicron strains than the original vaccine, both regimens offer low neutralization against BA.2.75.2, BQ.1.1, and XBB.1, “suggesting the potential of these new sublineages to dethrone BA.5 as the dominant lineage in circulation.” People who were infected with COVID-19 before receiving their bivalent booster developed higher and broader neutralization against the sublineages after the shot. “The results suggest that previous infection significantly increases the magnitude and breadth of neutralization for (the) BA.5-bivalent-booster and among the tested omicron sublineages, XBB.1 exhibits the highest level of immune evasion,” the authors wrote.