After offering boosters to the general population, she said, Israel was now averaging about half as many severe or critically ill patients as anticipated. She said boosters not only helped curb the spread of infection, but also “actually saved lives.”
Dr. William C. Gruber, a senior Pfizer vice president in charge of vaccine development, suggested that if the United States does not follow Israel’s lead, it could face more than five million more infections a year among people who received their second dose 10 months earlier, compared to those who got the second shot five months earlier.
“Israel could portend the U.S. Covid-19 future, and soon,” he said.
He said Pfizer’s data showed that a third shot elicited a robust antibody immune response that equaled or greatly exceeded the response after the second dose. Data also show, he argued, that breakthrough infections among vaccinated Americans are linked more to the ebbing power of the vaccine over time than to the Delta variant.
But committee members and some government officials appeared deeply skeptical. Dr. Philip Krause, one of the F.D.A. vaccine experts who wrote the medical journal review, criticized Pfizer’s presentation of data that had not been peer-reviewed or evaluated by the F.D.A., arguing that problems in the modeling in a study underpinning the company’s case understated the vaccine’s efficacy.
Dr. Oliver, the C.D.C. official, questioned attempts to draw a parallel between the United States and Israel, noting that Israel has only nine million residents and is less diverse than the United States. Notably, she also said that Israel defines a severe case of Covid-19 more broadly than the United States does, which might help explain why Israel reports more serious breakthrough infections among its vaccinated residents.
Another C.D.C. official, Dr. Amanda Cohn, asked Israeli officials why the spread of the virus there had recently intensified, despite a broad rollout of boosters. Dr. Alroy-Preis said that the Jewish holidays, along with the start of the school year, had contributed to what she suggested would be a temporary surge in cases.
Committee members also said they were concerned about a paucity of safety data in younger recipients of a booster dose, since studies have shown a higher risk of myocarditis, an inflammation of the heart muscle, in young men who received Pfizer-BioNTech’s vaccine. Several asked whether it would be better to wait for a booster vaccine devised specifically to fend off the Delta variant of the virus.