How exciting is the Pfizer vaccine?

摘要

US DRUG-MAKER Pfizer and its German partner BioNTech released some positive-looking results on 9 November from a clinical trial of their experimental covid-19 vaccine BNT162b2. The headline figure is "90 per cent effective". While the results are an important step towards a coronavirus vaccine, the news may not be quite as good as it first seems. What did Pfizer and BioNTech find? The results are from a phase Ⅲ clinical trial, the final stage of testing whether a vaccine or drug is both safe and effective. The companies gave the vaccine or a placebo to 43,538 participants in a double-blinded study, meaning that about half the people were dosed with the real thing and half with the placebo, but nobody knows who got what. They then waited until there were 94 confirmed cases of covid-19. As of 8 November, 38,955 participants had received two doses.