The long-awaited publication of peer-reviewed trial results of Pfizer’s mRNA COVID-19 vaccine has revealed evidence of the vaccine’s efficacy in patients aged 55-75 and other groups at high risk of severe disease.  

The study, published on Thursday in the New England Journal of Medicine, reports the data for about 44,000 participants across six countries in the phase III trial, half of whom received a saline injection as placebo.

Its publication comes as the UK continues its rollout of the BNT162b2 vaccine, sponsored jointly by Pfizer and BioNTech, and as the US prepares to start vaccinations this week after the FDA granted the vaccine emergency authorisation on Friday.

Eight COVID-19 infections were identified in the vaccine arm compared with 162 in the placebo arm, which resulted in the conclusion that vaccine was 95% efficacious overall.