Immune responses after two inactivated COVID-19 vaccine doses, a heterologous third dose and subsequent boosting with bivalent mRNA in adults.

ABSTRACT: To evaluate immune response and safety of a bivalent mRNA booster (ancestral/BA.4/5) vaccine in individuals who had received inactivated COVID-19 vaccine with different heterologous boost regimens. A prospective open-label study of bivalent ancestral/Omicron BA.4/5 was conducted. Healthy participants (age > 18) who completed two doses of inactivated COVID-19 vaccine and received any of these booster vaccines (Ad26.COV2.S, ChAdOx1, or mRNA-based) at least 12 months prior were enrolled. Immunogenicity data (anti-Spike (S) IgG, neutralization antibody titer (NT₅₀) against ancestral and XBB.1.5, and S-specific IFN-γ T- cells) was obtained at baseline, Day 28±7, and Day 90±14. Of 190 participants enrolled; 57 received Ad26.COV2.S, 66 received ChAdOx1, and 67 received mRNA vaccine as

SUBMITTER: Muangnoicharoen S 

PROVIDER: S-EPMC12748798 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature