Israel has become the first country to approve a fourth vaccine dose for people most vulnerable to COVID-19 as it braces for a wave of infections fuelled by the Omicron variant.
Nachman Ash, the director-general of the Health Ministry, announced the decision at a press conference late on Thursday.
He said the decision is based on early research, and that officials will consider expanding the administration of a fourth dose to more of the public as they assess the situation.
Israel was among the first countries to roll out Pfizer's coronavirus vaccine a year ago and began offering boosters last summer.
But it still saw a wave of infections blamed on the Delta variant and officials have warned of another driven by the fast-spreading Omicron.
Earlier on Thursday, Israel received its first shipment of pills that treat the worst effects of COVID-19.
It is among the first countries to receive Pfizer's Paxlovid, a pill that can be taken at home to ward off the most severe symptoms of the coronavirus. All the previously authorised drugs require an IV or injection.
Prime Minister Naftali Bennett said the shipment would help Israel to "successfully overcome the peak of the approaching Omicron wave".
Israeli media reported that the first shipment consists of 20,000 doses, with more expected as Pfizer ramps up production.
Israel currently has more than 20,000 patients, including 94 who are seriously ill.
At least 8,243 people have died from COVID-19 in Israel since the start of the pandemic.