Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine.
Level 2 - randomized trial
Multinational, observer-blinded, randomized controlled trial
PubMed 33301246 · doi:10.1056/NEJMoa2034577
What was done
In an ongoing multinational, placebo-controlled, observer-blinded trial, 43,548 participants aged 16 years or older were randomized 1:1 to receive two doses 21 days apart of either placebo or 30 μg of BNT162b2 (a lipid nanoparticle-formulated, nucleoside-modified RNA vaccine encoding SARS-CoV-2 spike protein). Primary endpoints were vaccine efficacy against laboratory-confirmed Covid-19 and safety.
What was found
A total of 43,448 participants received injections (21,720 BNT162b2, 21,728 placebo). For Covid-19 cases occurring at least 7 days after the second dose, 8 occurred in the BNT162b2 group compared with 162 in the placebo group, reflecting a vaccine efficacy of 95% (95% credible interval, 90.3 to 97.6). Subgroup efficacy across age, sex, race, ethnicity, BMI, and coexisting conditions was generally 90% to 100%. Severe Covid-19 with onset after dose 1 occurred in 1 BNT162b2 recipient versus 9 placebo recipients. Common adverse effects were mild-to-moderate injection-site pain, fatigue, and headache, with low and similar incidence of serious adverse events across groups.
Why it matters
This pivotal trial demonstrated high short-term efficacy and an acceptable safety profile for an mRNA-based vaccine against symptomatic Covid-19 across diverse populations.
Limits
Follow-up was limited to a median of 2 months, precluding long-term assessments of durability and rare adverse events. Participants under 16 years of age were not included, and the abstract provides no data on asymptomatic infection or transmission.
Cited by
- supports The original randomized controlled trials for the mRNA COVID-19 vaccines enrolled a total of 75,000 participants.