Dickerman BA, Gerlovin H, Madenci AL, et al. - Studies have revealed more than 90% effectiveness of the messenger RNA (mRNA)–based vaccines BNT162b2 and mRNA-1273 against coronavirus disease 2019 (Covid-19). Researchers aimed to report on their comparative effectiveness for a range of outcomes across diverse populations.

• Using the electronic health records, a target trial was emulated including US veterans who received a first dose of the BNT162b2 or mRNA-1273 vaccine between January 4 and May 14, 2021, during a period marked by predominance of the SARS-CoV-2 B.1.1.7 (alpha) variant.

• According to the risk factors, recipients of each vaccine were matched in a 1:1 ratio.

• A total of 219,842 persons were included in each vaccine group.

• Vaccination with mRNA-1273 or BNT162b2 was linked with a low 24-week risk of Covid-19 outcomes, although lower risks were observed with mRNA-1273 vs BNT162b2.

• This pattern remained consistent across periods marked by alpha- and delta-variant predominance.