Israel considers fourth dose but some experts say it's premature

But some scientists warned that the plan could backfire, because too many shots might cause a sort of immune system fatigue, compromising the body’s ability to fight the coronavirus. A few members of the government’s advisory panel raised that concern with respect to the elderly, according to a written summary of the discussion obtained by The New York Times…

In addition to concerns that a fourth shot in less than a year could actually weaken immunity, some experts said Israel’s government had still not made the most of other options, such as vaccinating more of the unvaccinated or giving a third shot to about a million eligible citizens who have so far not received one.

Along with the generally sparse knowledge about Omicron, the effect of a fourth dose against the new variant is also unknown. But the country’s medical experts point to waning immunity in those 60 or older, who were the first to receive the third shot starting in August.