Link to original NYT article: https://www.nytimes.com/2021/12/23/world/middleeast/israel-vaccine-4th-dose.html?smid=tw-nytimes&smtyp=cur
. . . 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. . .
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.
Israeli researchers from the Health Ministry and several academic institutions presented data to the advisory team that made the recommendation for the fourth shot on Tuesday. The presentation, obtained by The Times, showed a doubling of the rate of infection from Delta among the 60-plus age group within four or five months of the third shot.
There was no clear indication of reduced efficacy against severe illness.