Pfizer and BioNTech's COVID-19 vaccine showed 94 percent efficacy in a real-world study conducted in Israel involving 1.2 million people. The findings published in the New England Journal of Medicine showed that the vaccine performed as well as it did in the clinical trials. In this study, all persons who were newly vaccinated during the period from December 20, 2020, to February 1, 2021, were matched to unvaccinated controls in a 1:1 ratio according to demographic and clinical characteristics. Each study group included 596,618 persons.
Study outcomes included documented infection with SARS-CoV-2, symptomatic Covid-19, COVID-19-related hospitalization, severe illness, and death. The researchers analyzed data from Clalit Health Services (CHS), the largest of four integrated health care organizations in Israel. That a vaccine will perform as well in the real world as it does in the highly controlled setting of a clinical trial is not a given, noted senior author Ran Balicer, Director of the Clalit Research Institute of Israel, health news site STAT reported on Wednesday.