As US Health Body Debates Booster Dose, Spotlight On Israeli Study

A third dose of the Pfizer Inc.-BioNTech SE Covid vaccine can dramatically reduce rates of Covid-related illness in people 60 and older, according to data from a short-term study in Israel.

Starting 12 days after the extra dose, confirmed infection rates were 11 times lower in the booster group compared with a group that got the standard two doses, the analysis released Wednesday by the New England Journal of Medicine found. Rates of severe illness were almost 20 times lower in the booster group.

Early versions of the highly anticipated analysis have been cited by Biden administration officials, including the president's Covid medical adviser, Anthony Fauci, as they push for a booster program scheduled to start Monday. The Israeli analysis is expected to be highlighted at a meeting of Food and Drug Administration advisers reviewing Pfizer's application for clearance of the booster shots.

Response to the proposed U.S. booster rollout has been mixed. Fauci, Centers for Disease Control and Prevention Director Rochelle Walensky and FDA Acting Commissioner Janet Woodcock have expressed support, provided the additional shots pass muster from regulators and public health officials. Meanwhile, two top FDA vaccine staffers have announced plans to step down this year, a sign of possible skepticism for the plan.

Peter Marks, head of the FDA center in charge of vaccines, said the agency isn't facing pressure to clear the way for the Biden proposal.

"There's no political pressure here," he said in a forum sponsored by Research!America, a scientific advocacy group. "There is our own scientific interest in making sure we get it right."

Briefing Documents

FDA staff and Pfizer on Wednesday each released briefing documents ahead of the Friday meeting of agency advisers. Pfizer's presentation suggested that data show that the efficacy of its vaccine is waning and that booster shots will help restore it to protective levels.

The FDA staff report took a more moderate stance, pointing out that current regimes are still effective against severe illness and death from Covid. The staff said it hasn't yet closely reviewed the Israeli data, and that it will be presented at the Friday panel meeting.

The study from Israel followed more than 1.1 million Israel residents, all 60 years or older, who had been fully immunized with the Pfizer vaccine. Researchers at Weizmann Institute of Science, Technion-Israel Institute of Technology, the Israel Ministry of Health, Tel Aviv University and other collaborators compared infection and illness rates in those who got a third dose to those who didn't.

A major caveat to the analysis is that it is based on short-term follow-up. Israel's booster campaign started July 30, and the study took place through Aug. 31. Infection rates were calculated 12 days after boosters were administered to give them time to take effect.

In a viewpoint piece published Monday in The Lancet medical journal, a group of top researchers -- including the two FDA officials preparing to step down -- argued that most people don't need a booster shot now. The piece noted that the short-term benefit seen in Israel didn't necessarily imply that a booster would lead to long-term benefit.