Ahead of a highly anticipated meeting that could influence how soon coronavirus booster shots become widely available in the U.S., staff at the Food and Drug Administration appeared to take a neutral view of whether the agency should authorize a third dose of Pfizer's vaccine.
In a 23-page briefing document, which is meant to lay out the FDA's thinking on the issue before a meeting of expert advisers Friday, agency staff chose not to address evidence from a growing number of real-world studies that have raised alarm bells within the Biden administration of weakening protection from initial vaccinations.
"Some observational studies have suggested declining efficacy of Comirnaty over time against symptomatic infection or against the Delta variant, while others have not," the reviewers said in the document, using the brand name for Pfizer's vaccine. "[B]ut FDA has not independently reviewed or verified the underlying data or their conclusions."
Instead, agency reviewers carefully laid out the evidence being presented by Pfizer and the standards by which authorization of a booster shot would be evaluated. Much of that evidence consists of data on declining antibody levels following primary vaccination, rather than on a comprehensive accounting of efficacy versus COVID-19.
In its own documents submitted ahead of the meeting, Pfizer emphasized how antibody levels decline six months after a second dose, arguing that the broad authorization of boosters is "potentially an urgent emerging public health issue." Pfizer also pointed to data from Israel, which suggested that "protection against COVID-19 wanes approximately 6 to 8 months following the second dose." The FDA did not discuss that data in its prepared document.
Israeli health officials will speak to the committee on Friday, too, likely giving the chance for a more thorough vetting of data that the Biden administration has often referred to in public statements on the booster question.
FDA staff made clear, however, that they believe available data show the vaccines authorized in the U.S. "still afford protection against severe COVID-19 disease and death."
The meeting comes at a critical time, given it's only three days before the Biden administration's target for beginning rollout of booster shots more widely. Federal officials, set on curbing the high numbers of cases and deaths from the delta variant, said in August that Americans could start receiving booster shots as early as Sept. 20, pending FDA clearance.
"Recent data makes clear that the protection against mild and moderate disease has decreased over time," said Vivek Murthy, the U.S. surgeon general, during the Aug. 18 announcement.
While the administration initially suggested an interval of eight months between the first two vaccine doses and a third, the committee will be discussing administration of Pfizer's booster dose at six months, according to the FDA's document.
When to roll out boosters broadly has seemingly become a point of tension between the Biden administration and officials at the FDA and Centers for Disease Control and Prevention. Following the Aug. 18 announcement of its plans, the Biden administration was criticized for getting ahead of the scientific decision-making process, which remains ongoing with Friday's meeting.
This misalignment reportedly played a role in the unexpected retirements of Marion Gruber and Philip Krause, two top FDA officials and vaccine reviewers who are set to leave the agency at the end of the month. The pair were among the authors of an article published in the medical journal The Lancet earlier this week, which argued booster doses are not yet needed for the general public.
“Even if some gain can ultimately be obtained from boosting, it will not outweigh the benefits of providing initial protection to the unvaccinated," the scientists, which included top leaders at the World Health Organization, wrote.
Notably, Gruber will deliver an introduction during Friday's meeting, which is set to start at 8:30 a.m. The meeting will focus on Pfizer's coronavirus vaccine, although Moderna has also started the process of applying for FDA authorization of its booster shot.
Health officials have stressed the need for more data from Johnson & Johnson before making any decisions on an additional dose for people who received that vaccine.