An elderly Israeli man receives a Pfizer vaccine shot.

Breaking down statistics from Israel's Gertner Institute and KI Institute, ministry officials said that among people aged 60 and over, the protection against infection provided from 10 days after a third dose was four times higher than after two doses.

A third jab for over 60-year-olds offered five to six times greater protection after 10 days with regard to serious illness and hospitalisation. 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 health ministry has said immunity has diminished over time for seniors and younger people as well.

Most vaccinated people who fell severely ill in Israel were over 60 and with underlying health conditions.