ABSTRACT
We report SARS-CoV-2 neutralizing antibody titers in sera of triple-vaccinated individuals who received a booster dose of an original monovalent or a bivalent BA.1- or BA.4/BA.5-adapted vaccine, or had a breakthrough infection with Omicron variants BA.1, BA.2 or BA.4/BA.5. A bivalent BA.4/BA.5 booster or Omicron-breakthrough infection induced increased Omicron-neutralization titers compared with the monovalent booster. The XBB.1.5 variant effectively evaded neutralizing-antibody responses elicited by current vaccines and/or infection with previous variants.
Subject(s)
Breakthrough Pain , COVID-19ABSTRACT
The recently emerged Omicron variant is the most antigenically distinct SARS-CoV-2 variant of concern to date. As the heavily mutated spike protein enables escape from neutralizing antibodies, we studied the neutralizing activities of sera after Omicron BA.1 and BA.2 infections of naïve and vaccinated individuals. We show that primary BA.1 infections yielded reduced neutralizing antibody titers against wildtype (WT), Delta, and BA.2, while serum samples from individuals after BA.2 infection showed no cross-neutralization against the other variants. Fully vaccinated individuals were still able to neutralize both Omicron sub-lineages up to three months after vaccination, and Omicron-breakthrough infections showed equal cross-neutralizing activities against WT, Delta, BA.1, and BA.2. Our data demonstrate that Omicron variants are able to enhance cross-neutralizing antibodies in pre-immune individuals. Primary infections with one of the Omicron sub-lineages, however, induced variant-specific neutralizing antibodies. In particular, BA.2 infections generated a sub-lineage-specific response, emphasizing its antigenic distance.