Israel is considering giving a third shot of the Pfizer/BioNTech COVID-19 vaccine to its elderly population even before FDA approval in order to help fend off the Delta coronavirus variant, a health official said on Monday.
US and European Union authorities are considering whether booster shots are needed for specific risk groups.
"This is the big dilemma. The decision is on our shoulders when we don't have the world's backing. It is a very complex decision," Health Ministry Director-General Nachman Ash told a health conference hosted by news website Ynet.
"On the one hand we want to see that it is safe and effective and to rely on our data examining whether there really is waning immunity, and on the other hand there is an outbreak and we want to stop this outbreak."
Pfizer is seeking US emergency authorization for a third dose of its vaccine, which it has said may help people maintain higher levels of protection. Israel began offering boosters to immune-compromised people this month on a case-by-case basis.
"We expect to publish more definitive data about our booster program and all accumulated data will be shared as part of the ongoing discussions with the FDA, EMA and other regulatory authorities in the coming weeks," Pfizer spokesperson Jerica Pitts said in an emailed statement.
Since the Delta variant began spreading in Israel in June, the health ministry has twice reported a drop in the vaccine's effectiveness against infection and a slight decrease in its protection against severe disease.
Some experts have criticised the ministry's analysis because of possible bias that could be skewing the data. Last week, it estimated the vaccine was only 41 percent effective at halting symptomatic infections over the past month. Protection against severe disease remained strong at 91 percent.
"I estimate that this data is true, it could be more or it could be less," Ash said. "But the signs are, at least here, that immunity is waning."
A decision should be made in the coming weeks, Ash said, and it would likely affect people either 60- or 70-years-old and up, the high-risk group first to get the jab when Israel began its vaccination drive in December.
Some experts said Israel should wait a little longer to receive more information about safety and effectiveness of a third shot. Authorities were better advised to get the vaccine to those who have not been inoculated yet at all, said Nadav Davidovitch, director of Ben Gurion University's School of Public Health.
Around 60 percent of Israel's 9.3 million population has been vaccinated and about a fifth of those eligible have so far chosen not to take the shot.
Israel lifted coronavirus restrictions by mid-June, after inoculations drove infections down to single digits and deaths to zero. But the surge of Delta infections that began shortly after has led the government to reimpose some curbs.
Around 100 people are presently hospitalized in severe condition and daily infections stand at around 1000 confirmed cases. The cabinet is hoping that the vaccines will allow it to avoid costly lockdowns by protecting those most vulnerable to severe disease, even as infections climb.
According to Eran Segal, data scientist at Israel's Weizmann Institute of Science, the vaccines have had a significant effect on the rate of infections that have deteriorated into severe cases.
During the first few weeks of Israel's previous outbreak, which began in December, around 4.3 percent of confirmed cases turned severe. Now, in the first few weeks of the present outbreak and with around 90 percent of the high-risk groups vaccinated, only 1.6 percent of people testing positive have fallen seriously ill, Segal said.
"I attribute this change to the vaccines - absolutely," he said.