Israel is giving some members of its population a third dose of Pfizer's COVID-19 vaccine, and it seems to be working.
Health Ministry data has shown that the booster shot has significantly improved protection from infection and serious illness among people aged 60 and older in the country.
That's compared to those who have had just two doses of the vaccine.
Authorities say that among the over 60s, protection against infection provided from 10 days after a third dose was four times higher than after two doses.
It also offers five to six times greater protection after 10 days against serious illness and hospitalization for those in that age group.
The findings were made available online on Sunday, though the full details of the study were not released.
They were on par with separate statistics unveiled last week by Israel's Maccabi healthcare provider, which has been administering booster shots to try to curb the highly contagious Delta variant.
Over 60s are particularly vulnerable to COVID-19. They were the first group to be inoculated when the vaccine drive began in late December.
Most vaccinated people who fell severely ill in Israel were over 60 and had underlying health conditions.
Israel started giving over 60s third jabs at the end of July.
But last week, it dropped the age of eligibility for a booster to 40, and included pregnant women, teachers and health care workers below that age.
Third doses are given only to those who received their second shot at least five months ago.
Around 1.5 million people out of the country's 9.3 million population have taken a third jab as of Monday.