Retrospective study finds 61% of vaccinated, boostered individuals neutralize Wuhan-Hu-1 SARS-CoV-2 variant

A retrospective cohort study analyzed neutralizing antibody responses in serum samples from 100 vaccinated and boostered individuals. The study examined responses against SARS-CoV-2 variants including Wuhan-Hu-1, B.1.351, B.1.617, and Omicron, with secondary outcomes assessing cross-neutralization and antibody-dependent enhancement (ADE). No comparator group was reported, and the study design was observational.

Results showed 61 of 100 serum samples (61%) effectively neutralized the Wuhan-Hu-1 variant. Among these Wuhan-Hu-1 neutralizers, 20.6% demonstrated cross-neutralization against B.1.351 and B.1.617 variants. Among those cross-neutralizers, 66.6% were able to neutralize the Omicron variant. The study also reported that individuals with both vaccination and previous infection showed stronger neutralizing responses than those with vaccination and booster only, though no effect sizes or absolute numbers were provided for this comparison. ADE was observed in 1 of 100 samples (1%) in monocyte-derived macrophages.

Safety and tolerability data were not reported. The study's key limitation is its retrospective design, which precludes causal inference. The findings represent in vitro neutralization assays from a single cohort without clinical outcome data. The practice relevance is limited to underscoring the importance of continuously reassessing vaccine strategies as viral evolution unfolds, but these laboratory findings should not be directly extrapolated to clinical efficacy.