According to today's New York Times article, a second booster shot of the Pfizer-BioNTech Covid vaccine provides additional short-term protection against Omicron infections and severe illness, according to a large new study from Israel focusing on adults ages 60 and over.
But that protection against infection 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 did not provide data on the effectiveness of a second booster in younger populations.
The rapid spread of the highly transmissible Omicron variant has intensified the discussion of whether second boosters are broadly necessary.
A previous study from Israel found that older adults who received a second booster were 78 percent less likely to die of Covid-19 than those who had received just one — though scientists criticized its methodology.