Israel on Friday started giving fourth Covid vaccine shots to people with weakened immunity, becoming one of the first countries to do so in hopes of countering a case surge driven by the Omicron variant.
The effort comes almost exactly one year after Israel began a massive vaccination drive on the back of a data-sharing accord with US pharmaceutical firm Pfizer.
Israel's health ministry on Thursday approved giving a fourth shot for immunocompromised people, the same day that authorities reported more than 4,000 new cases of the disease, a high not seen since September.
Heart transplant patients were among the first to receive the additional shots at Sheba hospital in Ramat Gan near Tel Aviv, where health workers received test injections this week.
"I was worried at the start but after speaking to my doctor I felt reassured that it was a good thing to do, that it would help," said a 50-year-old woman, Rinat Orion, among the first to receive the fourth shot.
Galia Rahav, a doctor, said: "We had good results with the third dose which only caused secondary effects such as light, localised pain. We can't wait to see the results of this fourth dose."
Cardiologist Yael Peled said it would "increase protection against coronavirus".
- 'Confront the wave' -
Israel on Friday also added residents of retirement homes and geriatric patients to those eligible to take the fourth dose.
"This decision was taken for fear of an increase in cases of contamination in such institutions that would endanger the health of these people," the health ministry said.
Prime Minister Naftali Bennett has said Israel, which was among the first countries in the world to offer a third shot to the general public, will be a trailblazer for the fourth jab.
"Israel will lead the way in administering a fourth vaccine to the Israeli people," he said.
Chile has announced it will also offer a fourth shot to at-risk people starting in February, while health authorities in Britain and Germany are considering following suit.
More than four million people out of an Israeli population of 9.2 million have received three shots of coronavirus vaccine.
The health ministry said Thursday that Israel will not let up in its fight against the latest Covid-19 variant.
"Our strategy to confront Omicron is clear: the stronger the wave, the more protection we'll need to confront it," the ministry said.
On another front in the battle against the coronavirus pandemic, an Israeli El Al plane flew in Thursday from Belgium carrying a shipment of Pfizer's anti-Covid pill, Paxlovid.
On Friday, Israel recorded a 24-hour tally of 4,916 new coronavirus cases, an increase of 152 percent over the same day last week.
According to researchers at Jerusalem's Hebrew University, new daily infections could rise to 15,000 or even 20,000 within the next 10 days.
A total of almost 1.4 million cases of Covid infection, including 8,243 deaths, have been officially recorded in Israel.