Pfizer booster has 95.3% efficacy against COVID-19 relative to two doses

Embargoed until: Publicly released: 2022-03-24 16:00

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The Pfizer booster has an efficacy of 95.3 per cent relative to the first two doses, according to the company's ongoing Phase 3 trial results. The randomised controlled trial followed 5000 double-dosed people who received the booster, and 5000 who received a placebo, about 10 months after their initial vaccinations. The researchers say among those who hadn't previously had COVID-19, six boosted participants tested positive during the trial compared to 123 placebo participants. The trial took place when Delta was the dominant COVID-19 variant.