The FDA’s advisory panel voted unanimously Friday that booster doses of the Pfizer vaccine should be available to people 65 and older and people at high risk of severe disease. That recommendation is likely to be amended to include other groups like healthcare workers. Assuming the FDA uses the panel’s recommendation, that means the plan to offer booster shots on Sept. 20 may well go forward—just not for everybody.
That was actually the second vote of the meeting, after the panel decided not to extend the Pfizer’s vaccine approval to include a booster dose for everybody age 16 and over. That vote failed 16 to 2.
Wait, why can’t we all get boosters?
The booster question has been controversial among medical and public health experts for a while now, and there was hope that the FDA would get to see some extra data that would settle some of the open questions. What we knew before this was that people who got two doses are still very well protected against severe disease, including hospitalization and death, but that some data suggests that their protection against mild infections might be fading.
That data is tough to untangle, though. You could blame the increased breakthrough cases on fading immunity from the vaccine. Or, you could argue that the vaccine is just as effective as it ever was, and what we’re seeing is evidence that Delta is better at evading immune protection. There’s not enough information to say for sure which of those is happening, or whether it’s a mix of both.
The data presented at the meeting didn’t do much to clarify things. Officially, the panel was only supposed to be considering the results of a clinical trial that Pfizer conducted, but that trial was tiny—just over 300 people. To supplement that, the FDA had some Israeli scientists present data on vaccine effectiveness in their country. Israel experienced a surge in COVID cases despite a large proportion of the population being vaccinated; they began giving boosters in July and saw that the vaccine’s effectiveness seemed to improve after that. Still, some panel members had doubts about whether this data was enough to prove that boosters really work.
Another concern was that it wasn’t clear that the benefits of a booster would outweigh the risks in young people. Young men, especially, are at risk of a rare complication called myocarditis; it occurs in about 1 of every 20,000 who get the vaccine. In older people, the benefit of protection from COVID-19 clearly outweighs the small risk posed by a booster dose; in younger people, the panelists weren’t convinced.
And finally, some of the panelists questioned whether a universal booster is actually going to have any effect on the pandemic. We (unlike Israel) have a huge proportion of the population that is not vaccinated, and these are the people who are spreading most of the virus. If vaccinated people are occasionally able to transmit the coronavirus, and a booster makes that transmission less likely, that’s not going to make much of a difference to the population as a whole. It’s also not going to be very helpful to the person who was vaccinated, because they were already well-protected against severe disease.
A subject that didn’t come up at the meeting, but that has been discussed elsewhere, is that of vaccine equity. It’s hardly fair, when you take a global perspective, to give vaccine doses to already-vaccinated people for a tiny benefit, when you could give them to people who are still unvaccinated. In the US, most people who want a vaccine have had the chance to get one. In other countries around the world, that’s not the case, and vaccines are still in short supply. The World Health Organization has advised against boosters for this reason.
What happens next?
If the FDA goes with their panel’s recommendation (which technically they aren’t required to), they are likely to announce that Pfizer boosters are considered emergency-authorized for:
People age 65 and over
People at increased risk of severe disease as a result of COVID infection (probably defined the way CDC does, which includes people with a variety of medical conditions)
And possibly healthcare workers and others who are at high risk of exposure to COVID as part of their job.
That last caveat was added after the vote. Some members argued that preventing even mild infections is important in healthcare workers, since they could transmit the disease to patients and also since hospitals can’t afford to be even more understaffed.
After the FDA pronouncement, expect the CDC’s advisory panel, ACIP, to meet to make official recommendations on who should get booster doses. The White House’s plan to administer boosters on Sept. 20 has always had the caveat that the FDA and CDC must go through their usual process first. ACIP’s meeting has not yet been announced, so expect this situation to develop over the weekend.