Israel will start offering a third dose of Covid-19 vaccinations to people aged over 60, becoming one of the first countries to provide a booster shot.
The jabs will begin on Sunday as part of a "complementary vaccination campaign" for people who were fully vaccinated more than five months ago, Prime Minister Naftali Bennett said.
As concern mounts over the fast-spreading Delta variant, Mr Bennett said: "I call on all elderly people who have already been vaccinated to receive this additional dose."
About 55% of Israel's nine-million population has been double vaccinated, most with the Pfizer-BioNTech jab, thanks to a massive campaign launched in late December after an agreement with its producers.
"Israel has already vaccinated 2,000 immunosuppressed people with a third dose, with no severe adverse events," Mr Bennett said.
"And now we're rolling out a national third dose campaign."
Israeli President Isaac Herzog will receive the booster this morning.
'Decision based on evidence'
"The decision was based on considerable research and analysis, as well as the rise in risk of the Delta variant wave," Mr Bennett said.
Israel has recorded more than 1,400 Covid-19 cases in the past 24 hours.
More than 15,000 active cases are currently identified, including 151 people hospitalised in a serious condition, according to the health ministry.
"This third dose can save lives," Health Minister Nitzan Horowitz said.
Israel's digitised medical databases allowed for rapid large-scale studies, and its initial vaccine rollout of the jab was among the world's fastest.
Case numbers dropped dramatically, and in early June Israel eased many restrictions.
But infections soon rose again, prompting the health ministry to reimpose the wearing of masks in enclosed public places.
Last month, health officials announced they would open up vaccination to children as young as 12, while earlier this week, they said those aged five to 11 at risk of serious health complications could be vaccinated from 1 August.