Effectiveness of mRNA-1273 and BNT162b2 Vaccines in Qatar

To the Editor:

Growing evidence suggests that coronavirus disease 2019 (Covid-19) vaccines differ in effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or severe Covid-19,^1-3 but data from controlled studies that include head-to-head comparisons of the immunity induced by these vaccines are lacking. We conducted a study to compare the protection afforded by the mRNA-1273 (Moderna) vaccine with that…