Comparing the Safety and Immunogenicity of homologous (Sputnik V) and heterologous (BNT162B2) COVID-19 prime-boost vaccination

ABSTRACT Studies have shown increased immunogenicity from heterologous boosting. This study specifically assessed boosting with Pfizer-BioNTech in Sputnik V vaccination regimens. Reactogenicity was assessed through adverse events. Immunogenicity was assessed by comparing serum anti-Spike (Anti-S) protein antibody and neutralizing antibody titers before booster administration and after 30 days. A total of 428 participants were recruited in the heterologous arm and 351 in the homologous arm. Adverse events were more frequent in the heterologous arm (p<0.001). No serious adverse events were reported in either arm. Amongst 577 individuals who completed the study, Anti-S antibodies were 14.8 times higher after heterologous boosting, and 3.1 times higher after homologous boosting (p<0.001). Similarly, heterologous boosting showed a 2 fold increase in neutralizing antibodies, compared to a 1.6 fold increase in homologous boosting (p<0.001). In conclusion, both boosting regimens elicited an immunological response, nonetheless heterologous Pfizer-BioNTech showed a higher immunological response, with more adverse effects. ARTICLE SUMMARY LINE Both homologous and heterologous boosting are effective in eliciting an immunological response, however heterologous boosting with Pfizer-BioNTech elicited a higher immunological response, with more adverse effects.