Immunogenicity of the booster dose COVID-19 vaccine after complete primary series of inactivated vaccine (Sinovac) and viral vector vaccine (AstraZeneca) with full and half dose of mRNA vaccine

Results showed that headache, joint pain, and diarrhea were more frequent in the 15 ug- than the 30 ug-BNT162b2 groups, whereas joint pain and chilling were more frequent in the 100 ug- than the 50 ug-mRNA-1273 groups. No significant differences in immunogenicity were detected. These findings demonstrated that the reduced dose of mRNA vaccines elicited antibody response against the SARS-CoV-2 delta and omicron variants that were comparable to the standard dose.