The Pfizer Inc. and BioNTech SE Covid-19 vaccine appeared to stop the vast majority of recipients in Israel from becoming infected, providing the first real-world indication that the immunization will curb transmission of the coronavirus.
The vaccine, which is being rolled out in a national immunization program that began Dec. 20, was 89.4% effective at preventing laboratory-confirmed infections, according to a copy of a draft publication that was posted on Twitter and confirmed by a person familiar with the work. The companies worked with Israel’s Health Ministry on the preliminary observational analysis, which wasn’t peer-reviewed. Some scientists disputed its accuracy.
The results, also reported in Der Spiegel, are the latest in a series of positive data to emerge out of Israel, which has given more Covid vaccines per capita than anywhere else in the world. Almost half of the population has had at least one dose of vaccine. Separately, Israeli authorities on Saturday said the Pfizer-BioNTech shot was 99% effective at preventing deaths from the virus.
If confirmed, the early results on lab-tested infections are encouraging because they indicate the vaccine may also prevent asymptomatic carriers from spreading the virus that causes Covid-19. That’s not been clear because the clinical trials that tested the safety and efficacy of vaccines focused on the ability to stop symptomatic infections.
Pfizer and BioNTech said they are working on a real-world analysis of data from Israel, which will be shared as soon as it’s complete. Spokespeople declined to comment on unpublished data.
The study wasn’t designed to accurately measure a reduction in transmission of SARS-CoV-2 because it used national testing data without accounting for differences in testing rates between vaccinated and unvaccinated people, said Zoe McLaren, an associate professor in the school of public policy at the University of Maryland Baltimore County.
