Cross-neutralizing antibody responses among individuals with or without bivalent vaccine: a six-month prospective cohort study

Description

Vaccine protection fades unevenly across variants, and Hye Hee Cha and ten co-authors tracked that fading for six months in 79 healthcare workers in a 2026 study. The workers were grouped by history: prior Omicron infection, bivalent vaccination, both, or neither, and their neutralizing antibodies were measured against the original strain and two Omicron subvariants.

At three months, infection followed by vaccination produced clearly higher neutralization of both subvariants than either exposure alone. By six months that hybrid group still held the highest titers, while the infected-but-unvaccinated group's antibodies had sagged. The authors argue the ordering matters for future campaigns. In a previously infected population, the booster is not redundant insurance. It is the step that makes protection both broader and longer, against a virus that keeps resurfacing.

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Source: https://europepmc.org/articles/PMC13172796