A man receives a fourth dose of the coronavirus disease vaccine after Israel’s Health Ministry approved a second booster for the uncompromising at Sheba Medical Center in Ramat Gan, Israel. Reuters

Fourth jab ‘partially’ effective against Omicron – study

Fourth doses of the Pfizer and Moderna vaccines against Covid-19 are only “partially” effective for the Omicron variant of the virus, the authors of an Israeli trial said Monday.

A team from Sheba Medical Centre near Tel Aviv began conducting a trial in December on fourth doses of coronavirus vaccines, inoculating 154 hospital personnel with Pfizer jabs and 120 other volunteers with Moderna doses.

Preliminary results of the trial “have shown that the vaccines are safe and have shown to produce substantial antibodies, but are only partially effective in defending against the Omicron variant,” the hospital said in a statement.

Professor Gili Regev-Yochay, who leads the study, said that while there was an increase in antibodies after administering a fourth dose, it nonetheless “only offers a partial defenser against the virus” for those infected with the Omicron variant.

The vaccines were “extremely effective against the earlier variants,” Regev-Yochay noted.

Israel was among the first countries to launch mass immunisation campaigns for its population.

It then began offering booster shots last summer, and has since greenlighted fourth shots for elderly and vulnerable populations.

More than 537,000 Israelis have received a fourth dose of vaccine, according to the health ministry’s latest figures.

More than 80 per cent of Israel’s adult residents have received two coronavirus vaccine shots and more than half have also been given a booster.