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 The companies and Israel’s Health Ministry worked together on the preliminary observational analysis, which has not yet been peer-reviewed.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