Safety and immunogenicity of heterologous ChAdOx1-nCoV19 and BNT162b2 vaccination: A meta-analysis of the heterologous COVID-19 vaccination outcomes

INTRODUCTION: Here, we systematically assessed the safety and immunogenicity of the heterologous ChAd/BNT vaccination regimens. MATERIALS AND METHODS: We evaluated the immunogenicity by the geometric mean titers ratio (GMTR) of the neutralizing antibody and anti-spike IgG. The safety of heterologous ChAd/BNT vaccination was evaluated using the pooled risk ratios (RRs) calculated by the random-effects model about the adverse events. Our study was registered with PROSPERO, CRD42021265165. RESULTS: Eleven studies were included in the analyses. Compared to the homologous ChAd/ChAd vaccination, the heterologous ChAd/BNT vaccination showed significantly higher immunogenicity in terms of the neutralizing antibody and GMTR of anti-spike IgG, but at the same time displayed higher incidence of total adverse reactions, especially for the local adverse reactions. Moreover, heterologous ChAd/BNT vaccination showed similar immunogenicity to the homologous BNT/BNT vaccination (GMTR of neutralizing antibody and anti-spike IgG) and similar safety. DISCUSSION: Heterologous ChAd/BNT vaccination showed robust immunogenicity and tolerable safety.