TEL AVIV — Israel's Health Ministry on Thursday announced plans to start a coronavirus booster campaign for adults over 60 who received their second shot at least five months earlier, because of risks posed by the vaccines' apparent waning efficacy and the current wave of covid-19 cases.

In discussions with Israel's four national health funds, the ministry said the inoculation campaign would begin Sunday and would be available at nursing homes and government-funded health clinics.

"Reality has proven it: The vaccines are safe; they are proven to protect against serious illness and death," Israeli Prime Minister Naftali Bennett said in a televised statement Thursday. "As with the flu vaccine, which needs to be re-administered from time to time, so too is the case here."

Bennett said Israel's 60-year-old president, Isaac Herzog, would be the first to receive the booster shot, on Friday morning.

He urged all eligible Israelis to get vaccinated if they hadn't yet done so and encouraged them to contact their elderly relatives to make an appointment for a third dose.

"We must ensure that vaccinations outpace the pandemic," he said.

Just before midnight Wednesday, ministry experts had agreed to recommend, by an overwhelming majority, administering a third dose of vaccine to older adults.

This action coincided with the release of a paper by executives from the pharmaceutical giant Pfizer reporting that its coronavirus vaccine had strong but slightly diminished effectiveness six months after inoculation.
The company suggested that booster shots would soon be needed.

On Thursday morning, the head of the Israeli nursing homes union said that facilities across the country were already preparing the logistics to administer the booster shots.

Despite the lack of regulatory approval in the United States and Europe and the absence of definitive data about the effectiveness of booster shots in preventing serious illness and mortality, the experts concluded that promoting boosters for older Israelis could offer the best chance to stem the recent spike in infections.

In the past six weeks, cases in Israel have jumped from the single digits to more than 2,000 a day. The soaring cases, mostly because of the delta variant, have not led to a corresponding rise in the number of seriously ill and hospitalized patients.

Health Ministry data shows that recent infections in the vaccinated occurred mostly among those who were first to get inoculations, in January and February — priority groups that included most people with preexisting conditions.

The Health Ministry panel said Wednesday that protection against serious illness for those over 60 who were vaccinated in January has dropped from 97 percent to 81 percent.

For those over 60 and vaccinated in March, it fell to 94 percent. The panel added that 93 percent efficacy was maintained for people 40 to 59 years old.

Health Ministry data shows that vaccine protection against hospitalization for people with the delta variant remains at 91 percent but drops to 40 percent for milder infections and symptoms.

Israeli health experts have been divided on how to translate the relatively preliminary data into government policy, especially given starkly contrasting research from Britain, which has a vaccination rate similar to Israel’s.

A study published by British health authorities in the New England Journal of Medicine showed that two weeks after the administration of the second dose, the Pfizer vaccine is 88 percent effective against the delta variant, only slightly less than its 93 percent protection for the alpha variant.

Some health experts say that the Israeli studies showing far less vaccine protection over time are skewed because they mostly focused on covid hot spots and elderly populations. Others have argued that the findings could be an accurate reflection of the fact that Israel was among the first nations in the world to achieve wide-scale vaccination.

“Because we were the first to vaccinate extensively, we have no one to learn from,” said Nachman Ash, director of the Health Ministry, before the panel meeting on Wednesday night.

Because of its small size, meticulously digitized public health-care system, ethnically heterogeneous population and its leaders’ close relationship with Pfizer CEO Albert Bourla, Israel has been seen as a test case for the rest of the world, publishing data on the vaccine in return for a regular shipment of doses.

That has remained the case even as the neighboring Palestinian territories have lagged ­behind in their efforts to ­vaccinate their populations, recently rejecting a vaccine swap deal on grounds that the doses were too close to their expiration date.

The disparity has resurfaced an argument among human rights organizations that Israel has a legal responsibility to provide vaccine doses in the territories it occupies.

In the past two weeks, relying on its still steady supply, Israel has gone forward with administering third doses of the Pfizer vaccine to a limited number of severely immunocompromised adults, including transplant recipients and cancer patients, in efforts to boost protection for the most vulnerable.

Opposition leader and former prime minister Benjamin Netanyahu, who was the first Israeli to receive a dose of the Pfizer vaccine in December, has been a vocal advocate for the third shot for all Israelis older than 60. His office said a serological test showed he had a low covid antibody count. He has since been seen double-masking in the Knesset, according to the Israeli news site Walla.

Israeli experts say the decision to kick-start a booster shot policy is made possible by an expected Aug. 1 delivery of millions of Pfizer doses, as some of Israel’s current stockpile is set to expire.

“Israel can do this because we have the doses,” said Eyal Leshem, an infectious-disease specialist at Sheba Medical Center in central Israel. “But also, unlike other countries which don’t have the regulatory flexibility to say this is an emergency, Israel has decided, strategically, that it is willing to move on with intervention that is reasonable, clinically and scientifically, but not yet proven. It’s not the way we traditionally regulate and approve and distribute vaccines, but these are not normal times.”