Pre-Omicron Israeli research: People 50+ who got 3rd shot had 90% lower death rate

Researchers looked at data of over 840,000 people who got booster; paper co-author says study ‘unequivocally’ shows value of extra dose against Delta strain

A couple receive their third dose of the COVID-19 vaccine at Shaare Zedek hospital, on August 17, 2021, in Jerusalem. (Olivier Fitoussi/Flash90)
A couple receive their third dose of the COVID-19 vaccine at Shaare Zedek hospital, on August 17, 2021, in Jerusalem. (Olivier Fitoussi/Flash90)

Israeli research carried out before the emergence of the Omicron variant of the coronavirus found that people over the age of 50 who received a third dose of the Pfizer-BioNTech vaccine had 90 percent lower mortality than those who did not get the booster.

The research, based on data from the Clalit health maintenance organization and published in the New England Journal of Medicine, examined those who had received their second dose of the vaccine at least five months earlier. Clalit is the largest of Israel’s HMOs.

In July, Israeli became the first country in the world to start a campaign to administer a third dose of the vaccine in the face of falling efficacy against a wave of the Delta strain of the virus. Those aged 50 or over became eligible for a booster in August.

Researchers studied the data of 843,208 individuals, of whom 758,118 (90%) received the booster (the third dose) during the period of the study.

In that group, there were 65 deaths due to COVID-19 — 0.16 per 100,000 persons per day.

In the group of vaccinated individuals who did not receive the booster, 137 died — 2.98 per 100,000 persons per day.

A woman receives a COVID-19 vaccine shot at a mobile Magen David Adom center on Dizengoff Square in Tel Aviv, on August 14, 2021. (Miriam Alster/Flash90)

The statistics were adjusted for sociodemographic factors and coexisting medical conditions. Individuals were counted as having received the booster only from one week after they were administered the third dose.

Doron Netzer, head of community medicine at Clalit, told the Walla news site that the study showed “unequivocally that the booster vaccine is significantly associated with reducing the risk of mortality from coronavirus, including from the Delta strain.”

Netzer, named as a co-author on the paper, added that the third shot of the vaccine was incredibly effective in a way that is rarely seen.

“Very few medical interventions can be attributed to a tenfold reduction in the risk of mortality, as we found for the booster vaccine,” he said.

However, it remains unclear exactly how effective the vaccine is in the face of the Omicron strain.

Israelis, some wearing face masks, shop at Jerusalem’s Mahane Yehuda market, December 2, 2021. (Yonatan Sindel/Flash90)

BioNTech and Pfizer said Wednesday that their vaccine is “still effective” against the variant after three doses.

An Omicron-specific version of the jab, which BioNTech began developing on November 25, will be available “by March,” they said in a statement.

Pfizer said that a third dose of its COVID vaccine “increases the neutralizing antibody titers by 25-fold compared to two doses against the Omicron variant,” based on an initial laboratory study.

The initial data, said Pfizer, shows that “a third dose provides a similar level of neutralizing antibodies to Omicron as is observed after two doses against” previous strains of COVID-19.

Initial research from a South Africa-based laboratory indicated that the efficacy of two doses of the Pfizer vaccine drops in the face of the Omicron variant, but that those with two doses plus a previous infection were well protected. There were no participants included in the study who had received three doses of the vaccine, since booster shots are not yet available in South Africa.

In South Africa, where the Omicron variant was first discovered, a woman is tested for COVID-19. (AP Photo/ Shiraaz Mohamed)

“These results are better than I expected,” tweeted Alex Sigal, a researcher at Africa Health Research Institute who authored the study. “The more antibodies you got, the more chance you’ll be protected from Omicron.”

As of Monday, Israel has confirmed 21 cases of the Omicron variant.

Fears of the spread of the new COVID mutation led Israel to shut its borders to foreigners in late November and institute a mandatory three-day quarantine for all those who arrive — even those with three vaccine doses.

From Thursday, confirmed carriers of the Omicron COVID-19 variant will be required to quarantine for 14 days, instead of the 10 days mandated for confirmed carriers of other coronavirus strains.

Scientists from both the World Health Organization and the United States government have said this week the Omicron variant appears to be no worse than other coronavirus strains — but that more research is still necessary.

Amy Spiro and AFP contributed to this report.

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