An Israeli hospital has administered fourth Covid-19 vaccine doses to a test group, as the country considers approving the measure for vulnerable populations in a bid to outpace a surge in infections fuelled by the Omicron variant.

The Sheba Medical Centre study in Ramat Gan outside Tel Aviv “will zero in on efficacy of the vaccine in producing antibodies, and safety, in order to ascertain if a fourth vaccine is needed in general,” a spokesman said. The 150 subjects are all medical staff, Reuters reported.

A Health Ministry expert panel last week recommended that Israel become the first country to offer a fourth vaccine dose — also known as a second booster — to those aged over 60, those suffering from compromised immune systems, and medical workers.