Believed to be the largest such study in the world to date

Israel’s largest HMO finds vaccines 92% effective in preventing serious illness

Clalit survey of 1.2 million Israelis, half of them immunized, finds that shots drive down symptomatic COVID by 94%

A woman receives a COVID-19 vaccine injection at Clalit COVID-19 vaccination center in Jerusalem, on February 8, 2021. (Olivier Fitoussi/ Flash90)
A woman receives a COVID-19 vaccine injection at Clalit COVID-19 vaccination center in Jerusalem, on February 8, 2021. (Olivier Fitoussi/ Flash90)

A massive study by Israel’s largest health provider indicates that the Pfizer-BioNTech vaccine is 94 percent effective in preventing symptomatic COVID-19, and 92% effective in averting serious cases of the disease.

The survey by the Clalit Health Services HMO compared 600,000 fully vaccinated individuals — 170,000 over 60 and 430,000 between the ages of 16 and 59 — with 600,000 unprotected Israelis. Believed to represent the largest such study in the world to date, it found the vaccine to be highly protective from both symptomatic infections and serious symptoms, shoring up previous studies on the shots.

“The previous studies dealt with infections, but not with symptoms and therefore can’t be compared to Pfizer’s clinical research,” said Dr. Ran Balicer, an epidemiologist who directs health policy planning at Clalit, in an interview with Channel 12. “Now, for the first time, we are comparing the vaccinated group with a control group with similar characteristics to see if the vaccine works ‘by the book.'”

After accounting for factors such as age, “we can state clearly: The vaccine prevents serious illness also among those 70 and older, for whom there wasn’t enough data in Pfizer’s study,” said Balicer, who analyzed the data along with several Israeli researchers and a team from Harvard University.

Professor Ran Balicer, head of innovation at Clalit, Israel’s biggest health services provider, in Tel Aviv on June 10, 2020 (EMMANUEL DUNAND / AFP)

Starting from a week after the second shot, the vaccine is 91%-99% effective in preventing serious COVID-19 cases, the study found. Those figures will likely be narrowed down further as time goes by and additional immunized Israelis arrive at that mark. The data indicated the shots’ effectiveness could grow even further from two weeks after the second shot, said Balicer, though he said additional analysis would be needed in the coming weeks.

Last week, another Israeli healthcare provider that has vaccinated half a million people with both doses of the Pfizer vaccine said that only 544 people — or 0.1% — have been subsequently diagnosed with the coronavirus, there have been four severe cases, and no people have died. That means the effectiveness rate stands at 93%, Maccabi Healthcare Services announced on Thursday, after comparing its immunized members to a “diverse” control group of unvaccinated members.

As of Sunday night, over 3.8 million Israelis have received the first dose of the vaccine, and 2.5 million received both vaccines.

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