Strategies for rolling out vaccination against Coronavirus Disease 2019 (Covid-19) varied across countries. A key question is whether delaying administration of the second vaccine dose to vaccinate the largest number of people in the shortest time, in situations of limited vaccine supplies and high incidence, could avert more disease cases, hospitalizations and deaths than the current protocol of a second dose shortly after the first dose. BNT162b2 (Pfizer-BioNTech) vaccine effectiveness against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Qatar was recently reported with focus on individuals who completed 14 days after the second dose. 1 Here, we provide a follow-up analysis of how vaccine protection develops week-byweek after the first dose.

Data for SARS-CoV-2 were extracted from Qatar’s nationwide digital-health information platform. The platform hosts the national centralized SARS-CoV-2 databases that captured all vaccination records, polymerase chain reaction (PCR) testing, and COVID-19 hospitalizations and deaths since epidemic start. 1 The study was conducted from 1 February to 31 March 2021, the period of rapid mass vaccination scale-up. Vaccine effectiveness was estimated using the test-negative case–control study design. 2 Cases and controls were matched one-to-one by age, sex,