Steensels D, Pierlet N, Penders J, et al. - Researchers performed a direct comparison concerning humoral immune responses between the SARS-CoV-2 messenger RNA (mRNA) vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna).

• Participants were 1,647 health care workers at a tertiary care center (Ziekenhuis Oost-Limburg, Belgium) who were scheduled for vaccination with 2 doses of either mRNA-1273 or BNT162b2.

• After the second dose of each vaccine, comparison of antibody levels was done for the entire cohort; for those previously infected vs uninfected; and by age group (< 35, 35-55, and > 55 years) among previously uninfected individuals.

• The SARS-CoV-2 mRNA-1273 vaccine (Moderna) was demonstrated to induce a significantly higher humoral immunogenicity compared with the BNT162b2 vaccine (Pfizer-BioNTech), in infected as well as uninfected participants, and across age categories.

• This difference is possibly due to the higher mRNA content in mRNA-1273 vs BNT162b2 and the longer interval between priming and boosting for mRNA-1273 (4 weeks vs 3 weeks for BNT162b2).