The initial impact of a national BNT162b2 mRNA COVID-19 vaccine rollout.

OBJECTIVE: This study examined the initial impact of a national BNT162b2 vaccine rollout on SARS-CoV-2 infections in Qatar. METHODS: All individuals who had completed ≥14 days of follow-up by 16 March 2021 after receiving the BNT162b2 vaccine were included. This study calculated incidence rates (IR) and their 95% confidence intervals (CI) during days 1-7, 8-14, 15-21, 22-28, and >28 days post-vaccination. Poisson regression was used to calculate incidence rate ratios (IRR) relative to the first 7-day post-vaccination period. RESULTS: A total of 199,219 individuals with 6,521,124 person-days of follow-up were included. SARS-CoV-2 infection was confirmed in 1877 (0.9%), of which 489 (26.1%) were asymptomatic and 123 (6.6%) required oxygen support. The median time from first vaccination to SARS-CoV-2 confirmation was 11.9 days (IQR 7.7-18.2). Compared with the first 7-day post-vaccination period, SARS-CoV-2 infections were lower by 65.8-84.7% during 15-21, 22-28, and >28 days (P < 0.001 for each). For severe COVID-19, the incidence rates were 75.7-93.3% lower during the corresponding time periods (P < 0.001 for each). CONCLUSION: The results were consistent with an early protective effect of BNT162b2 vaccine against all degrees of SARS-CoV-2 severity.