This study investigated the immunogenicity and safety of a heterologous prime-boost COVID-19 vaccination strategy using ChAdOx1 (viral vector) followed by MVC-COV1901 (spike-2P subunit). 100 healthy adults who received a first dose of ChAdOx1 received a booster dose of either ChAdOx1 or MVC-COV1901. The MVC-COV1901 booster resulted in significantly higher neutralizing antibody titers against both the wild-type and Delta variant of SARS-CoV-2 compared to the ChAdOx1 booster. Both B and T cell responses were substantially enhanced by the heterologous schedule, particularly with a shorter prime-boost interval. No serious adverse events were reported.
