Four months into one of its worst Covid-19 outbreaks, Israel is seeing a sharp drop in new infections and severe illness, aided by its use of vaccine boosters, vaccine passports and mask mandates, scientists and health officials said.
Israel was struck by its fourth coronavirus wave in June, fuelled by the fast-spreading Delta variant.
Rather than imposing new lockdown measures, the government bet on a third booster dose of the Pfizer Inc PFE.N/BioNTech BNTX.O vaccine for people age 12 and up, mandated face coverings and enforced use of a "Green Pass" - proof of vaccination, recovery from the illness or a negative test for the virus - at restaurants and other venues, even for children.
Since peaking in early September, daily infections in Israel have fallen more than 80%, with severe cases nearly halved.
"Day by day we are breaking the Delta wave," Prime Minister Naftali Bennett said on Tuesday, crediting government policy for "close, smart and flexible management allowing life alongside coronavirus."
Israel's "Living with Covid" strategy, which has not come without cost or controversy, has kept schools and the economy open.
The Israeli Health Ministry on Thursday presented the latest safety and effectiveness data from its booster campaign to a panel of advisers to the US Food and Drug Administration considering authorization of additional booster shots.
The data show that among people over 60 - the first group to receive boosters - infections began declining rapidly about two weeks after third doses were administered, while still climbing among other age groups.
A data analysis by Doron Gazit and Yinon Ashkenazy of the Hebrew University's Covid-19 monitoring team showed the virus' reproduction rate - its ability to spread - began a sharp fall among each age group following the third shot.
Two months into the Delta wave, vaccinated people over the age of 60 made up more than half of severe Covid-19 cases. The majority were over 70 with health conditions that put them at higher risk.
Since administration of boosters, mostly unvaccinated, often younger, people are bearing the brunt of serious illness. They make up about 75% of hospitalized patients in severe condition, while those vaccinated with two or three shots account for a quarter of such cases.
A third dose has so far been effective in curbing severe breakthrough cases among vaccinated people age 40 and up, according to the health ministry.
There is less available data for teens and young adults. However, the ministry said its findings so far show that a third dose has not increased the risk of myocarditis, a rare heart inflammation, in younger people.
Ran Balicer, who heads the government's coronavirus expert advisory panel, said a combination of measures curbed the Delta surge.
"These include the masks mandate, the 'Green Passes', the massive testing both with PCR testing and rapid antigen tests. But undoubtedly, the most important impactful factor in bringing down the Delta summer surge was the mass vaccination campaign with booster doses," Balicer said.
In England, where boosters have been administered to roughly 5% of the population, masks have largely been abandoned and vaccine passports are not mandatory, COVID-19 cases are on the rise.
Some scientists said Israel's decision in late August to approve a third vaccine dose for young adults and teens was premature, lacking clear evidence of a benefit. They argue the focus should still be on convincing unvaccinated people to accept the shots.
The United States and several European countries have so far authorized boosters only for older adults, people with weakened immune systems or workers at high risk of coronavirus exposure.
The World Health Organization has pleaded with wealthier nations to hold off on boosters while many countries struggle to access vaccines.
"Israel rushed, even gambled, when it came to approving a third dose for the whole population and not to specific age groups as other countries did," said Hagai Levine, professor of epidemiology at the Hebrew University in Jerusalem.
"In the midst of a pandemic you sometimes have to make a decision based on partial evidence," Levine said. Nevertheless, "the jury is still out on third doses for the entire population."
Bennett has been criticized by some scientists for rejecting tougher measures that would have kept Delta infections lower from the start. They included government health officials who feared the "Living with Covid" policy exacted too heavy a toll.
"We have 1,400 people who died in this wave. So there are benefits to keeping the economy open and there is some cost to that," Sharon Alroy-Preis, head of public health at Israel's Health Ministry, told The Jerusalem Post conference on Tuesday.
By September, hospitals strained to care for Covid-19 cases that could have perhaps been avoided, doctors and health officials said.
"It's a good policy, but it has its price," said Yael Haviv-Yadid, head of the critical care ward at Sheba Medical Centre, whose unit saw an influx of young, unvaccinated patients. "The teams are very tired, burned out."
So far, 3.7 million people have taken a third shot, more than a third of Israel's population.
"Israel was the first country to deal with the combined challenge posed by the Delta variant and mass waning immunity, but it is definitely not the last" Balicer cautioned.
"Other countries that will be faced with this complex challenge will have to figure out their own balance," he added, "and the costs can be high."