Comparative analysis of human immune responses following SARS-CoV-2 vaccination with BNT162b2, mRNA-1273, or Ad26.COV2.S

SARS-CoV-2 vaccines BNT162b2, mRNA-1273, and Ad26.COV2.S received emergency use authorization by the U.S. Food and Drug Administration in 2020/2021. Individuals being vaccinated were invited to participate in a prospective longitudinal comparative study of immune responses elicited by the three vaccines. In this observational cohort study, immune responses were evaluated using a SARS-CoV-2 spike protein receptor-binding domain ELISA, SARS-CoV-2 virus neutralization assays and an IFN- gamma ELISPOT assay at various times over six months following initial vaccination. mRNA-based vaccines elicited higher magnitude humoral responses than Ad26.COV2.S; mRNA-1273 elicited the most durable humoral response, and all humoral responses waned over time. Neutralizing antibodies against the Delta variant were of lower magnitude than the wild-type strain for all three vaccines. mRNA-1273 initially elicited the greatest magnitude of T cell response, but this declined by 6 months. Declining immunity over time supports the use of booster dosing, especially in the setting of emerging variants.

Automated summary

This study observed the immune responses elicited by the SARS-CoV-2 vaccines BNT162b2, mRNA-1273, and Ad26.COV2.S. The results showed that mRNA-based vaccines elicited higher magnitude humoral responses, with mRNA-1273 inducing the most durable response, but all humoral responses decreased over time. Neutralizing antibodies against the Delta variant were lower for all three vaccines. The T cell response initially induced by mRNA-1273 was the most significant, but declined after six months. Therefore, declining immunity over time emphasizes the importance of booster doses.