A third dose of Pfizer-BioNTech's Covid-19 vaccine has significantly improved protection from infection and serious illness among people aged 60 and older in Israel, compared with two shots, new findings showed on Sunday.
The findings, published by the Israeli Health Ministry, were presented to a panel of vaccination experts on Thursday and uploaded to its website on Sunday, although full details of the study were not released.
The figures were on par with statistics reported last week by Israel's Maccabi healthcare provider, one of several organisations administering booster shots to try to curb the Delta coronavirus variant.
Breaking down statistics from Israel's Gertner Institute and KI Institute, the ministry said that among people aged 60 and over, the protection against infection from 10 days after a third dose was four times higher than after two doses.
A third shot for those older than 60 offered five to six times greater protection after 10 days against serious illness and hospital admission.
That age group is particularly vulnerable to Covid-19 and in Israel was the first to be inoculated when the vaccine drive began in late December.
In recent weeks, the ministry has said immunity has diminished over time for seniors and younger people.
Most vaccinated people who became severely ill in Israel were 60 and over, and with underlying health conditions.
Israel started administering third shots to that age group on July 30.
On Thursday it dropped the age of eligibility for a booster to 40, and included pregnant women, teachers and healthcare workers below that age.
Third doses are given only to those who received their second shot at least five months ago.
The US has announced plans to offer booster shots to all Americans, quoting figures showing diminishing protection. Canada, France and Germany have also announced booster campaigns.
Israel, fighting an outbreak of the Delta variant since June, now has one of the world's highest infection rates per capita.
Almost 1.5 million people out of the country's 9.3 million population have had a third shot.