Israel's Rising COVID Infection Rate Revives Controversy Over Fourth Dose

The BA.2 variant is responsible for 60 to 80 percent of Israel's new COVID cases, although no solid information shows a fourth dose offers greater protection against infection and serious illness

Ido Efrati
Ido Efrati
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COVID test in Tel Aviv, Israel, on Tuesday
COVID test in Tel Aviv, Israel, on TuesdayCredit: מוטי מילרוד
Ido Efrati
Ido Efrati

The recent rise in Israel's infection rate has revived the debate whether to get a fourth dose of the coronavirus vaccine.

The country's R number – the average number of people each coronavirus carrier infects – has risen to 1.39. The number is calculated using data from the last 10 days. The pandemic is contracting as long as the infection rate is less than 1. 

According to Health Ministry data, 13,384 new cases were diagnosed Tuesday. The number of seriously ill patients, however, edged down to 300. Due to the rising caseload, the government’s coronavirus advisory panel met Tuesday for the first time since February 7.

The omicron wave in Israel has been receding since February, though there has been an uptick in the infection rate and daily infections over the last week. Since March, the infectious BA.2 variant has replaced omicron as the dominant strain in the country and is estimated to account for 60 to 80 percent of new cases.

In early January, when the omicron variant was raging in Israel, the Health Ministry recommended that people over 60, medical staffers and people in high-risk groups get a fourth dose of the vaccine. At the end of that month, it expanded eligibility for the fourth dose to anyone 18 and older. 

But to date, only 741,000 Israelis have opted to receive it. Even amidst Israelis who rushed to get both the first two doses and the booster were skeptical about the fourth, though now, with the virus spreading again, some are rethinking the issue.

Nevertheless, in contrast to the previous shots, there’s no solid information about whether the fourth dose offers greater protection against infection and serious illness than the third. The Health Ministry has yet to formulate a clear stance on this issue.

In January, the advisory panel was shown initial data based on an analysis of 600,000 people who received the fourth dose. That data indicated that a fourth dose offers twice as much protection against infection as the third and three to five times as much protection against serious illness.

Last week, however, a study conducted by Sheba Medical Center in Tel Hashomer hospital concluded in its interim findings that while the fourth dose did reduce symptomatic illness and increase antibody levels, it wasn’t particularly effective at preventing infection by omicron, which BA.2 resembles. That study involved 600 people, of whom 270 received the fourth dose and the rest received three.

The Sheba study, conducted by Prof. Gili Regev-Yochay, found that a month after the fourth dose was administered, 18 to 20 percent of the people who received it had contracted omicron, whereas 25 percent of the people who only got three doses contracted omicron during that month. However, 31 to 41 percent of those who only got three doses developed symptomatic illness, compared to only 15 percent of those who got the fourth dose.

“Even if it’s not very effective at preventing infection, the fourth dose is very effective at preventing hospitalizations, complications and deaths,” argued Dr. Yasmin Maor, head of the infectious disease unit at Wolfson Medical Center in Holon and a member of the advisory panel.

“It’s true that omicron is a milder disease, but on the other hand, morbidity was so widespread that it ultimately led to a high number of hospitalizations and deaths,” Maor added. And BA.2 is thought to be around 30 percent more infectious than omicron.

But Dr. Oren Kobiler, a virologist from Tel Aviv University, is less convinced of the necessity of a fourth dose. 
“I think the fourth dose increases antibodies for a short time, and that it provides partial protection against infection better than the third dose, but not more than that,” he said. 

Regev-Yochay, who heads Sheba’s infectious disease unit, said her study found that someone who got the fourth dose and then gets the virus “develops a slightly milder case, but they get infected no less than other people.” 

Nevertheless, she said, the fourth dose is important for people who need additional protection – “obviously people in risk groups, but also healthy young people who want a little more protection.” And since there are no safety issues with the extra dose, from that standpoint, “there’s no real reason to refrain.”

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