Air passengers arriving from the UK on Monday were tested at the Sheba government hospital for the covid mutation. On Wednesday, the hospital reported that three had tested positive for the UK variant, the fourth with an unknown strain. They had been sent into isolation upon landing at Ben Gurion. The coronavirus director Prof. Nahum Ash commented that the Pfizer vaccine, which has been administered to more than 70,000 Israelis people since Sunday is almost certainly effective against the mutated strain. Israel has meanwhile halted all incoming flights from overseas. Israeli travelers were given a deadline for their return: those arriving up to 10 p.m. Wednesday night are allowed to spend their period of isolation at home, while those landing later are to be transferred directly to the special quarantine hotels. A committee was set up to approve exceptions, such as sick or elderly people or mothers of infants.