However, the FDA said that observational studies do not unanimously support the suggestion that vaccination effectiveness degrades over time, while the overall data shows that all three U.S. approved or licensed vaccines – from Pfizer-BioNTech, Moderna, and Johnson & Johnson – still protect against serious illness and death.
“There are many potentially relevant studies, but the FDA has not independently reviewed or verified the underlying data or its conclusions,” the agency said, adding that some of these studies – including data from Israel – would be discussed on Friday.
The Israeli data, some of which is due to be released on Wednesday, has shaped the Biden government’s efforts to offer boosters to most adults next week. In the absence of this, federal scientists and other public health experts have questioned the move to boosters, as available data shows that the vaccines still offer high levels of protection against serious illness, hospitalization, and death in most age groups.
“Known and unknown biases” can affect the reliability of observational studies, the FDA warned.
“Also, US-based studies have been conducted on the effectiveness of the post-approval [the Pfizer-BioNTech vaccine] may most accurately represent the vaccine’s effectiveness in the US population, “the agency said.
Still, the FDA confirmed that the companies met the pre-defined success criteria in their booster study.
The third dose of the vaccine was “well tolerated,” Pfizer said, with no serious side effects or deaths reported. Side effects commonly reported were mild to moderate injection site pain, fatigue, chills, and sore muscles.
Pfizer’s booster shot application would be for anyone aged 16 and over. If members of the FDA’s Vaccine Advisory Committee vote to recommend boosters, the FDA and the CDC’s external advisory committee could act within days to allow the Pfizer booster to be used. The FDA is not bound by the recommendations of its advisory boards, but often follows them.
The Biden government’s goal of introducing boosters by September 20 has sparked controversy within the FDA. Two of the agency’s leading vaccine scientists, Marion Gruber and Philip Krause, recently decided to retire this fall – partly out of frustration with the proposed launch of the boosters.
Gruber, director of the FDA’s Office of Vaccines Research and Review, will speak at the FDA advisory committee meeting on Friday.
More about side effects: About 5 percent of study participants – mostly female – had swollen lymph nodes within four days of the shot, Pfizer said. All but one of the disease, a known side effect of the vaccine, were rated as mild.
“Since Dose 3 is a booster, it is not surprising that there is stimulation of a lymph node response from vaccination with a significant increase in neutralizing antibodies after Dose 3,” said Pfizer.
None of the participants experienced myocarditis or pericarditis, two inflammatory heart conditions that have been linked to the vaccine, especially in men under 30 years of age.
Pfizer also recommends giving the booster dose six months after a patient’s second of two starting doses, rather than the eight months suggested by the Biden government’s top health officials. The final decision as to when is up to the federal regulatory agencies of the FDA and CDC.
What’s next: The FDA will publish on Wednesday the questions that the advisory committee will consider at its meeting on Friday. In addition to the booster shot application from Pfizer and BioNTech, the agency is considering a booster application from Moderna.