HealthDay News — Recipients of mRNA-1273 versus BNT162b2 had a lower risk for breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during predominance of the delta variant, according to a research letter published online Jan. 20 in the Journal of the American Medical Association.
Lindsey Wang, from the Case Western Reserve University School of Medicine in Cleveland, and colleagues identified breakthrough SARS-CoV-2 infections that occurred between July and November 2021, when the delta variant predominated, in fully vaccinated individuals receiving two doses of an mRNA vaccine, who had not received a booster shot and had no previous infection (62,628 individuals in the mRNA-1273 cohort and 574,538 in the BNT162b2 cohort).
The researchers found that from July to November 2021, the monthly incidence of breakthrough infections increased in both cohorts and was higher in the BNT162b2 than the mRNA-1273 cohort, reaching 2.8 and 1.6 cases per 1,000 person-days, respectively, in November. Compared with the matched BNT162b2 cohort, the mRNA-1273 cohort had a significantly lower risk for breakthrough infections after matching (hazard ratio, 0.85). The 60-day hospitalization rate was 12.7 and 13.3 percent for mRNA-1273 and BNT162b2 recipients, respectively; 60-day mortality was 1.14 and 1.10 percent, respectively. Among the matched cohorts, the risk for 60-day hospitalizations was lower for mRNA-1273 versus BNT162b2 recipients (hazard ratio, 0.80). Mortality did not differ significantly between the cohorts.
“Although there is a difference in breakthrough infections, both vaccines are highly protective against SARS-CoV-2 infection and especially against the most severe consequences of infection,” a coauthor said in a statement.