Why Israel Went for a Second COVID Booster Shot

While many doctors and scientists have criticized the move, expert advisory panel members say concerns about the highly infectious omicron COVID variant tipped the scales

Ido Efrati
Ido Efrati
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Bennett receiving the booster shot in August.
Bennett receiving the booster shot in August.Credit: Amir Levy
Ido Efrati
Ido Efrati

An expert advisory panel’s decision to recommend a fourth dose of the coronavirus vaccine for senior citizens on Tuesday was made with very little information about either its efficacy or its risks.

Many doctors and scientists immediately criticized the recommendation, but committee members said concerns about the spread of the highly infectious omicron variant tipped the scales.

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The vast majority of the panel’s 90 members supported recommending a fourth shot for people over age 60, immunosuppressed people and medical staffers. They concluded that a second booster posed no risk and that there was a chance it would help prevent infection among high-risk groups.

The plan had been to discuss the issue only in another few weeks or even months, based on more complete information. But with omicron spreading, several committee members said they feared that waiting would be worse. “In another three weeks, it may be too late,” one explained.

Committee members said they weren’t certain that the effectiveness of the third dose is waning, since not enough studies have been done, and the data is unclear. This is apparently because not enough time has passed since Israel began giving the boosters and was the first country in the world to do so.

In an interview with Kan Bet radio on Wednesday, Dr. Tal Brosh, the panel’s coordinator, admitted that the U.S. pharmaceutical company Pfizer, the vaccine’s maker, had no information about the possible impact of a fourth dose. “Currently, no research has been done on this issue, and they certainly don’t have findings,” he said.

Asked whether such research should be done before going ahead with the second booster, Brosh answered, “We could study this and publish the results in a fine article in another two months. But at that point, it would have no impact. We can sit in our intellectual armchairs and say the third dose might protect us and the fourth dose might not add much benefit. But this is speculation.”

In any case, the information that was available to the panel supported a fourth dose. Data presented by Prof. Ron Milo of the Weizmann Institute of Science showed that the third shot’s effectiveness against the delta variant has waned over time, with a significant decline in its ability to prevent infection four months after being administered, panel members said.

Prof. Oren Tsimhoni, head of the infectious diseases department at Kaplan Medical Center in Rehovot and a member of the committee, said it was this data that persuaded him to vote for the fourth shot.

“The data showed that after four months, the risk of infection was three times higher than with a fresh dose,” he said. “Originally, I wasn’t in favor, but after I saw that data, I changed my mind completely. I concluded that it was impossible to ignore the data, which shows a rise in morbidity even with no connection to omicron, apparently due to the waning of the booster.”

“With regard to infection, there aren’t very many immune system agents at the site of the first encounter with the virus, in the mucus membrane, compared to the circulatory system and deep tissue, where the immune system manages to cope with the virus better, especially after three doses,” Tsimhoni said. “This explains why the effectiveness against serious illness is maintained, even though we see a steep drop in effectiveness against infection.”

Nevertheless, Tsimhoni said the whole discussion would have been postponed had rising infection rates and the spread of omicron not “forced us to decide quickly.”

“It’s an issue of risk management under conditions of uncertainty,” he continued. “The vast majority of [committee] members thought it was better to do something than to wait. When we reach 15,000 new cases a day, it will be too late.”

As for initial reports that omicron may cause less serious illness than delta, Tsimhoni said this wouldn’t be enough to offset “the insane rise in infections” enough to keep the number of hospitalized patients at a reasonable level.

The advisory panel was also shown laboratory research that examined the vaccine’s effectiveness against omicron, both immediately after the third shot and some months later. This research found that the antibodies produced by the vaccine were more effective shortly after the third dose was given.

“The big unknown that we still have no information about is the risk of serious illness,” said Prof. Zachi Grossman, chairman of the Israel Pediatric Association and another panel member. “This is critical information that would have a major impact and completely change the picture. But there’s already evidence of a waning of the booster, and it’s important to make a decision quickly.”

The panel also discussed whether to recommend the fourth dose or merely allow it. But Grossman said that merely allowing it wouldn’t persuade many people to get it. “From a moral and scientific standpoint, panel members need to stand behind the recommendation to vaccinate,” he explained.

Nevertheless, the recommendation has sparked considerable criticism, including from the medical and scientific communities. Some argued that the decision was made too hastily, on the basis of insufficient information. Others warned that it would undermine the effort to vaccinate children and deepen distrust of the vaccines among certain sections of the public.

For instance, Prof. Dror Mevorach, who heads the coronavirus unit at Hadassah Hospital, Ein Karem, tweeted that he would have opposed the recommendation had he been on the panel and urged the committee to reconsider it in another two weeks.

The Israeli Association of Public Health Physicians also said the panel should have waited for additional data before recommending a fourth dose. “We have an obligation to prepare for a serious wave of infections from omicron, but also to take into account that we don’t yet know how virulent it is and therefore avoid unfounded decisions,” it said in a statement.

A minority of panel members also thought the available information was insufficient to recommend a fourth dose. One of them was Dr. Dorit Nitzan, the World Health Organization’s emergency director for the European region.

“I understand the strong desire to protect at-risk groups,” she said, but added, “As always during this pandemic, Israel is a trailblazer, and I believe other countries will later follow suit.

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