Antibody Responses and Reactogenicity of a Heterologous, Full-Dose Messenger RNA-1273 Booster in Heavily SARS-CoV-2-Exposed CoronaVac-Vaccinated Health-Care Workers in Indonesia: A Real-World Observational Study.

Real-world data on heterologous boosting with messenger RNA (mRNA)-1273 (Moderna) after inactivated COVID-19 vaccination are limited. We report mRNA-1273 boosting in heavily SARS-CoV-2-exposed Indonesian health-care workers who received a two-dose CoronaVac 6 months prior. Between August and November 2021, we measured SARS-CoV-2 spike-specific IgG binding antibody (Bab) titers in all 304 participants, and neutralizing antibody titers in a random subset of 71 participants, on stored paired serum samples taken before and 28 days after a full-dose (100-μg) mRNA-1273 booster.