Immunogenicity and reactogenicity of heterologous ChAdOx1 nCoV-19/mRNA vaccination

• DOI: 10.5281/zenodo.5080642
• Publication Date: 2021-07-07
• Authors: Tina Schmidt; Verena Klemis; David Schub; Janine Mihm; Franziska Hielscher; Stefanie Marx; Amina Abu‐Omar; Laura Ziegler; Candida Guckelmus; Rebecca Urschel; Sophie Schneitler; Sören L. Becker; Barbara C. Gärtner; Urban Sester; Martina Sester
• Keywords: Reactogenicity; Heterologous; 2019-20 coronavirus outbreak

AbstractHeterologous priming with the ChAdOx1 nCoV-19 vector vaccine followed by boosting with a messenger RNA vaccine (BNT162b2 or mRNA-1273) is currently recommended in Germany, although data on immunogenicity and reactogenicity are not available. In this observational study we show that, in healthy adult individuals (n = 96), the heterologous vaccine regimen induced spike-specific IgG, neutralizing antibodies and spike-specific CD4 T cells, the levels of which which were significantly higher than after homologous vector vaccine boost (n = 55) and higher or comparable in magnitude to homologous mRNA vaccine regimens (n = 62). Moreover, spike-specific CD8 T cell levels after heterologous vaccination were significantly higher than after both homologous regimens. Spike-specific T cells were predominantly polyfunctional with largely overlapping cytokine-producing phenotypes in all three regimens. Recipients of both the homologous vector regimen and the heterologous vector/mRNA combination reported greater reactogenicity following the priming vector vaccination, whereas heterologous boosting was well tolerated and comparable to homologous mRNA boosting. Taken together, heterologous vector/mRNA boosting induces strong humoral and cellular immune responses with acceptable reactogenicity profiles.