The Pfizer-BioNTech COVID-19 vaccine was basically as effective in a study of 600,000 Israelis as in Pfizer's smaller clinical trials, researchers reported Wednesday in the New England Journal of Medicine. And the new study provided evidence Pfizer was unable to show, due to limited data in its trials, that the vaccine is equally effective in people 70 and over as in younger people.
The publisher results provide "scientifically validated real-world evidence of the effectiveness of the vaccine," said Ran Balicer, one of the study's chief authors and chief innovation officer at Clalit, Israel's largest health care provider.
The study compared 600,000 Israelis who had received the vaccine against 600,000 demographically similar Israelis who were not vaccinated. The vaccinated population was 57 percent less likely to develop any COVID-19 symptoms in the two to three weeks after getting the first dose and 94 percent less likely after getting the second shot. Those fully inoculated were 92 percent less likely to develop severe COVID-19 symptoms. One dose was 72 percent effective at preventing death.
"This is immensely reassuring," said the Mayo Clinic's Dr. Gregory Poland, who is not involved in the study, "better than I would have guessed." The Clalit Research Institute, Israel's Ben-Gurion University of the Negev, and Harvard University led the research.
Israel agreed to give Pfizer access to its data in exchange for extra vaccine supply, and it has now given more than half its population a first dose and fully inoculated about a third of the country. Its data is especially useful because Israel has now opened its vaccination campaign to everyone older than 16. This has also allowed Israel to experiment with the next stages of the pandemic. On Saturday, Israel began issuing special passports that allow vaccinated people access to concerts, gyms, hotels, and other public spaces.