2. How well does this vaccine work?
The trial needs to be completed to confirm that the vaccine works as well as the early results suggest. More than 43,000 people are in the Pfizer BioNTech trial, with half given the vaccine and the other half given a placebo (dummy) vaccine. So far 94 people have been confirmed to have coronavirus, with about 10 times as many people who had the placebo getting ill as who had the real vaccine.
But 94 isn’t many, and although it’s unlikely that the apparent benefit of the vaccine is showing up by chance, there isn’t enough data yet to be sure of its exact effect. The full results will be released when about another 70 people in the trial have been confirmed to have coronavirus, which is likely to be in the coming weeks.