An Israeli hospital will start giving a 4th Covid-19 vaccine shot to its 150 staff in a trial to know whether a second booster dose is necessary or not, the facility said. The staff members taking part in the trial had already received Health Ministry approval and got their booster shots on Aug 20. Sheba Medical Center near Tel Aviv said its trial would make the effectiveness clear of a fourth dose and help in health policy in Israel and other countries.

A Health Ministry panel of experts has advised a fourth dose of the Pfizer-BioNTech vaccine to citizens of Israel who are over age 60 to get a booster shot at least four months ago. But final approval by the ministry’s director-general is still pending amid discussions about whether enough scientific information is available to justify a new booster drive.