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Analysis‘We’re boldly going where no country has gone before’

How well does the vaccine work? Israel’s real-world stats can be globe’s guide

The international community will be watching Israel, where vital data is starting to emerge from the breakneck-paced mass inoculation campaign

Nathan Jeffay

Nathan Jeffay is The Times of Israel's health and science correspondent

A health worker prepare a vaccination against COVID-19 at a Clalit vaccination center in Jerusalem, on December 31, 2020 (Olivier Fitoussi/Flash90)
A health worker prepare a vaccination against COVID-19 at a Clalit vaccination center in Jerusalem, on December 31, 2020 (Olivier Fitoussi/Flash90)

Until now, Israel’s speedy coronavirus vaccination rollout has been the source of awe, envy (and some criticism) worldwide. But with the release of preliminary data on how hundreds of thousands of people have responded to the shots, it’s also set to be the source of groundbreaking insights expected to help bolster vaccination efforts globally.

Most notably, the data released Tuesday by the Health Ministry shows that the vaccine significantly cut down infection levels among sample sizes even before full protection kicks in after the second of two doses.

Medics have been tracking infection levels among some 600,000 people who received the Pfizer-BioNTech vaccine, a group almost 30 times bigger than the one involved in the large-scale Phase 3 trial that preceded the US Food and Drug Administration’s approval of the shot.

A Health Ministry official announced that the vaccine curbs infections by some 50 percent 14 days after the first of two shots is administered. She said that the data is preliminary, and based on the results of coronavirus tests among both those who have received the vaccine and those who haven’t, who are are serving as a de facto control group.

Separately, two of Israel’s four healthcare providers announced their own figures, which diverged somewhat from the Health Ministry’s data: Maccabi cited a 60% reduction in infections, and Clalit reported a smaller reduction.

Medical workers administer vaccinations at Hillel Yaffe Medical Center in Hadera (courtesy of Hillel Yaffe Medical Center)

Clalit’s innovation chief Ran Balicer, who also chairs the government’s expert advisory team on dealing with the pandemic, said that those who received vaccines have normal infection rates until immunity appears to kick in after about two weeks.

“Graphs diverge on day 14 with a 33% decline among the vaccinated elderly, without a similar trend among the unvaccinated,” he said. He added that more information would be forthcoming from more detailed peer-reviewed studies currently underway.

Maccabi reported that the rate of infection decreased from about 40 out of 100,000 people in the first 12 days after vaccination to about 15 per 100,000 on days 13 to 21 — a 60% reduction.

It’s unclear exactly why the figures vary, but one factor appears to be the fact that Maccabi included vaccinated people of all ages in its study, while Clalit didn’t.

During the period of the study, the vaccine was only officially available to those 60 years and up. Younger people who made the effort to find spare appointments are thought likely to be more health-conscious than the general population, so Clalit removed them from the study to increase “generalizability.”

There is also concern that people may be less likely to get tested for coronavirus after getting a shot, skewing the data.

Nonetheless, the numbers appear to offer the clearest evidence yet for how long it takes immunity to begin after getting the first dose of the Pfizer-BioNTech vaccine.

“I think it is amazing that within two to three weeks Israel has gathered data derived from hundreds of thousands of immunized people,” said immunity expert Cyrille Cohen, a member of the Health Ministry’s advisory committee on vaccines. “This can help answer crucial questions regarding the immediate protective effect of one dose of vaccine.”

With Israel beginning to give out second doses this week, the ongoing study will also soon shed light on how long it takes full immunity to take effect, and eventually give health officials more information on how long that immunity lasts, both key questions.

Doses of the Pfizer-Biontech COVID-19 coronavirus vaccine at a vaccination center in Magdeburg, eastern Germany, on December 27, 2020. (Ronny Hartmann / POOL / AFP)

“In a sense, Israel has become like a very large clinical trial,” Hadassah Medical Center virologist Rivka Abulafia-Lapid told The Times of Israel.

While the US and UK are both giving out more vaccinations than Israel in sheer numbers, they both lack the centralized electronic record-keeping of Israel’s four health maintenance organizations, which have been tasked with distributing the majority of the shots.

“Because everyone in Israel belongs to an HMO and their records are kept along with their background data, this means we’ll get a good picture of responsiveness to the vaccine, in context of age, gender, and existing medical conditions,” Abulafia-Lapid said.

People arrived to get vaccinated against the COVID-19 coronavirus at at a large vaccination center in Tel Aviv, on December 31, 2020. (JACK GUEZ / AFP)

The desire for Israeli stats is also thought to underpin Pfizer’s willingness to quickly supply Israel with vaccine doses.

Pfizer is expecting medical data in return for vaccines — publicly available information, according to the Health Ministry, though some analysts suspect it will be more revealing. Whatever is provided, it will mean that Pfizer doesn’t need to suffice with a general gaze at infection patterns, but will be viewing detailed information from the country’s highly advanced medical records system.

By early February, Israel is expected to be the only country with most of its elderly population fully vaccinated. A look at its data will give an unparalleled view of how the vaccine performs in a real-world setting for those that need it most.

Cyrille Cohen, head of the immunotherapy laboratory at Bar Ilan University. (courtesy of Cyrille Cohen)

“The efficacy, meaning its performance in trials, was 95%, but the big issue now is what happens in the real world,” said Cohen, who heads the immunotherapy laboratory at Bar Ilan University in Ramat Gan. “The sample of people in a clinical trial gives important information but it’s still a sample, like those used in polling before elections.”

Just as polling samples don’t always give an accurate picture of real voting patterns, clinical trials don’t necessarily give an exact picture of a vaccine’s effectiveness when it’s widely deployed in society.

During the Pfizer Phase III trial, some 8,700 people aged 56 to 85 years were given the shot. Israel has so far injected over a million people 60 and up with at least one dose, over 120 times the number included in the study. The scale of data available is mind-boggling, and each day tens of thousands more are being vaccinated.

“To paraphrase Star Trek, we’re boldly going where no country has gone before,” said Cohen. “Some countries are saying they will ‘wait and see’ before giving the vaccine. Israel, with its emphasis on a scientifically supported ‘choose life’ ethos, took a different approach — and we now look set to provide the real-world and vital results and observations that will hopefully give a good basis for others to stop waiting and embrace the vaccine.”

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