Israeli Data Suggests Possible Waning in Effectiveness of Pfizer Vaccine

The new numbers still show overwhelmingly strong protection against severe disease but diminished effectiveness against infection.

As Israel struggles with a new surge of coronavirus cases, its health ministry reported on Thursday that although effectiveness of the Pfizer-BioNTech vaccine remains high against severe illness, its protection against infection by the coronavirus may have diminished significantly compared with this winter and early spring. Analyzing the government’s national health statistics, researchers estimated that the Pfizer shot was just 39 percent effective against preventing infection in the country in late June and early July, compared with 95 percent from January to early April. In both time periods, however, the shot was more than 90 percent effective in preventing severe disease. Israeli scientists cautioned that the new study is much smaller than the first and that it measured cases in a narrower window of time. As a result, a much larger range of uncertainties flank their estimates, which could also be skewed by a variety of other factors.