Pfizer-BioNTech Shot Stops Covid's Spread, Israeli Study Shows

The Pfizer Inc. and BioNTech SE Covid-19 vaccine appeared to stop the vast majority of recipients in Israel becoming infected, providing the first real-world indication that the immunization will curb transmission of the coronavirus.

The vaccine, which was 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 The companies and Israel’s Health Ministry worked together on the preliminary observational analysis, which has not yet been peer-reviewed.

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. Nearly 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.

The early results on lab-confirmed infections are important because they show the vaccine may also prevent asymptomatic carriers from spreading the virus that causes Covid-19, something that hadn’t been clear so far. Stopping transmission in this way is a key factor as countries seek to lift contact restrictions and re-open economies.

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 Spokespeople declined to comment on unpublished data.

Four-fifths of the virus cases in Israel during the time period of the study, from Jan. 17 to Feb. 6, were the more transmissible strain first identified in the U.K. Israel’s vaccination drive began just before the so-called B.1.1.7 variant emerged, fueling infections and leading to a third lockdown on Jan. 8.

Through Feb. 6, about 27% of people aged 15 and older in Israel were fully vaccinated, with the Pfizer-BioNTech shot the only vaccine available in the country at the time. People were considered fully vaccinated and included in the analysis if the data collected were more than 7 days after they received their second dose.