Rüdiger Groß , Michelle Zanoni , Alina Seidel , Carina Conzelmann , Andrea Gilg , Daniela Krnavek , Sümeyye Erdemci-Evin , Benjamin Mayer , Markus Hoffmann , Stefan Pöhlmann , Alexandra Beil , Joris Kroschel , Bernd Jahrsdörfer , Hubert Schrezenmeier , Frank Kirchhoff , Jan Münch , Janis A. Müller
June 01 2021
Heterologous prime-boost schedules with vector- and mRNA-based COVID-19 vaccines are already administered, but immunological responses and elicited protection have not been reported.
We here analyzed a cohort of 26 individuals aged 25-46 (median 30.5) years that received a ChAdOx1 nCoV-19 prime followed by a BNT162b2 boost after an 8-week interval for reactogenicity, antibody responses and T cell reactivity.
Self-reported solicited symptoms after ChAdOx1 nCoV-19 prime were in line with previous reports and less severe after the BNT162b2 boost. Antibody titers increased significantly over time resulting in strong neutralization titers 2 weeks after the BNT162b2 boost. Neutralizing activity against the prevalent strain B.1.1.7 was 3.9-fold higher than in individuals receiving homologous BNT162b2 vaccination, only 2-fold reduced for variant of concern B.1.351, and similar for variant B.1.617. In addition, CD4 + and CD8 + T cells reacted to SARS-CoV-2 spike peptide stimulus 2 weeks after the full vaccination.
The heterologous ChAdOx1 nCoV-19 / BNT162b2 prime-boost vaccination regimen is not associated with serious adverse events and results in a potent humoral immune response and elicits T cell reactivity. Variants of concern B.1.1.7, B.1.351 and B.1.617 are potently neutralized by sera of all participants. These results suggest that this heterologous vaccination regimen is at least as immunogenic and protective as homologous vaccinations.