Isabel Kershner in The New York Times:
JERUSALEM — Israel, which leads the world in vaccinating its population against the coronavirus, has produced some encouraging news: Early results show a significant drop in infection after just one shot of a two-dose vaccine, and better than expected results after both doses. Public health experts caution that the data, based on the Pfizer-BioNTech vaccine, is preliminary and has not been subjected to clinical trials. Even so, Dr. Anat Ekka Zohar, vice president of Maccabi Health Services, one of the Israeli health maintenance organizations that released the data, called it “very encouraging.” In the first early report, Clalit, Israel’s largest health fund, compared 200,000 people aged 60 or over who received a first dose of the vaccine to a matched group of 200,000 who had not been vaccinated yet. It said that 14 to 18 days after their shots, the partially vaccinated patients were 33 percent less likely to be infected. At about the same time, Maccabi’s research arm said it had found an even larger drop in infections after just one dose: a decrease of about 60 percent, 13 to 21 days after the first shot, in the first 430,000 people to receive it.
On Monday, the Israeli Health Ministry and Maccabi released new data on people who had received both doses of the vaccine, showing extremely high rates of effectiveness. The ministry found that out of 428,000 Israelis who had received their second doses, a week later only 63, or 0.014 percent, had contracted the virus. Similarly, the Maccabi data showed that more than a week after having received the second dose, only 20 out of roughly 128,600 people, about 0.01 percent, had contracted the virus.