Because Israel tests people fairly comprehensively, the researchers were also able to estimate that the vaccine was 89.4% effective in preventing any detectable infection at all, including asymptomatic infections.

That finding, which is new, suggests that the vaccine could strongly suppress transmission of the virus between people and could help bring the outbreak to an end, a possibility Pfizer and the Israeli researchers say they are closely watching. “Israel provides a unique opportunity to observe the nation-wide impact of an increasing prevalence of immunity on Sars-Cov-2 transmission,” the authors wrote. Eric Topol, a doctor at Scripps Research in California, who reviewed the document, says that “the blocking of infections here speaks to the vaccine’s impact on asymptomatic transmission, which we’ve been unsure about.”

https://www.technologyreview.com/2021/02/19/1019264/a-leaked-report-pfizers-vaccine-conquering-covid-19-in-its-largest-real-world-test/ - https://www.technologyreview.com/2021/02/19/1019264/a-leaked-report-pfizers-vaccine-conquering-covid-19-in-its-largest-real-world-test/