Pfizer and Biontech report that their covid vaccine led to immunity in 90% of recipients in the first analysis of its effectiveness, far exceeding the 75% hoped for and the 50% that U.S. infectious disease chief Dr. Anthony Fauci said would be acceptable. The companies' stock soared on the news.
The analysis evaluated 94 confirmed Covid-19 infections among the trial's 43,538 participants. Pfizer and BioNTech said the case split between vaccinated individuals and those who received a placebo indicated a vaccine efficacy rate of above 90% at seven days after the second dose.
It means that protection from Covid-19 is achieved 28 days after the initial vaccination, which consists of a two-dose schedule.
