In a retrospective cohort study, both homologous and heterologous vaccinations were efficacious against Omicron variants. But, in the head-to-head comparison, the effect was stronger in individuals who got heterologous vaccination compared to those who got homologous immunization. Sachiko Ono et al. sought to compare the efficacy of BNT162b2 and mRNA-1273 booster doses after BNT162b2 primary immunization.

Patients 16 years of  age and more who had completed the BNT162b2 major vaccination were enrolled, and data on their infection status, vaccine type, vaccination status, gender, and age were obtained. The age ranges were 16-44, 45-64, 65-84, and ≥ 85 years. Employing age-stratified Cox regression adjusted for days after the second immunization, gender, and age, no booster vaccination against BNT162b2 and vaccine efficacy for mRNA-1273 were calculated. Utilizing random effects meta-analyses, the estimated hazard ratios (HR) for no booster vaccines and mRNA-1273 were integrated individually.

During the trial period, 26.4% (n = 40,849), 33.2% (n = 51,490), and 40.4% (n = 62,586) subjects who were administered no booster dosage, mRNA-1273, or BNT162b2 were identified respectively. The median ages for no booster dosage, mRNA-1273, and BNT162b2 were 47, 71, and 69 years, respectively. In relation to BNT162b2, the integrated HR was 0.62 for mRNA-1273 and 1.72 for no booster immunization. The efficacy of mRNA-1273 was comparable across age groups.

Vaccinations against Omicron variations are efficacious in both homologous and heterologous forms. However, the impact was greater in individuals who got heterologous immunization than in those who got homologous vaccination in the head-to-head comparison. These outcomes might assist in the improvement of decision-making and logistics in future immunization programs.