A second booster shot of the Pfizer-BioNTech Covid vaccine provides additional short-term protection against Omicron infections and severe illness among older adults, according to a large new study from Israel.

But the booster’s effectiveness against infection in particular wanes after just four weeks and almost disappears after eight weeks. Protection against severe illness did not ebb in the six weeks after the extra dose, but the follow-up period was too short to determine whether a second booster provided better long-term protection against severe disease than a single booster.

The study focused on adults ages 60 and older, and did not provide data on the effectiveness of a second booster in younger populations.

The findings, published on Tuesday in the New England Journal of Medicine, suggest that additional boosters are likely to provide fleeting protection against Omicron infections in older recipients, and are consistent with evidence that vaccine effectiveness against infection wanes faster than against severe disease.

“For confirmed infection, a fourth dose appeared to provide only short-term protection and a modest absolute benefit,” the researchers wrote.

I thought with the war n Ukraine, the world had gotten past this...