The Lancet Regional Health: Western Pacific · 22 authors, 10 centres
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This study evaluated plasma neutralizing antibody responses in 67 human volunteers with different vaccination or infection histories against SARS-CoV-2 Omicron subvariants. The central result is that heterologous vaccination with an inactivated vaccine primary series followed by an mRNA booster significantly increased neutralizing antibody titers compared to three doses of a homologous inactivated vaccine alone.
Using enzyme-linked immunosorbent assay and pseudovirus neutralization assays, the study found that in all groups, neutralizing activity was lower against Omicron subvariants than against G614, with XBB.1 showing the lowest activity. Critically, heterologous vaccination groups (e.g., inactivated vaccine primary series with an mRNA booster) had significantly higher geometric mean NT50 values (4- to 42-fold higher against Omicron subvariants) than the group receiving three doses of a homologous inactivated vaccine, whose titers were often below detection limits. The findings suggest a heterologous mRNA boosting strategy could enhance protection where inactivated vaccines were primarily used.
