mRNA-1273 COVID-19 vaccine effectiveness against the B.1.1.7 and B.1.351 variants and severe COVID-19 disease in Qatar.
Level 4 - case-series / case-control
Matched test-negative case-control study
PubMed 34244681 · doi:10.1038/s41591-021-01446-y
What was done
A matched test-negative case-control study was conducted in Qatar to assess the real-world effectiveness of the mRNA-1273 (Moderna) vaccine against SARS-CoV-2 infection with the B.1.1.7 (Alpha) and B.1.351 (Beta) variants, as well as against severe, critical, or fatal COVID-19 disease.
What was found
Vaccine effectiveness was negligible for 2 weeks after the first dose. Effectiveness against B.1.1.7 infection was 88.1% (95% CI: 83.7-91.5%) ≥14 days after dose 1 and 100% (95% CI: 91.8-100.0%) ≥14 days after dose 2. Effectiveness against B.1.351 infection was 61.3% (95% CI: 56.5-65.5%) after dose 1 and 96.4% (95% CI: 91.9-98.7%) after dose 2. Effectiveness against severe, critical, or fatal COVID-19 was 81.6% (95% CI: 71.0-88.8%) after dose 1 and 95.7% (95% CI: 73.4-99.9%) after dose 2.
Why it matters
This study provides real-world evidence that full vaccination with mRNA-1273 provides high protection against B.1.1.7 and B.1.351 variants, and substantially reduces severe COVID-19 disease even after one dose.
Limits
The abstract does not report the total sample size. The population comprised predominantly working-age adults, limiting generalizability to elderly or high-risk populations. Observational case-control designs remain subject to unmeasured confounding.
Cited by
- supports Against the Alpha and Beta variants of SARS-CoV-2, COVID-19 vaccines used in the United States were 90% to 95% effective at preventing symptomatic infection.