The advisory committee itself voted 18-0 to recommend a third dose of the Pfizer vaccine for those who are 65 and older or people at high risk for COVID, for instance, but under an emergency use authorization (EUA) which could be revoked at any time and is more limited in scope than a regular approval. But the regulatory and scientific drama could persist in years to come should the virus become endemic and continue to mutate, as many experts predict.

“This is a very generalist virus, it infects lots of different animals, and it’s already in lots of different animal populations. And so future versions of this virus are going to be part of the landscape,” said Gigi Gronvall, an immunologist, senior scholar, and associate professor at Johns Hopkins’ Bloomberg School of Public Health’s Center for Health Security. “I do think it’s kind of amazing that in just a couple of years time, we have vaccines that are as safe and effective as they are, though we have more work to do to get better drugs and therapeutics. But this isn’t going to go the way of smallpox or even polio, at least not anytime soon. It’s just too much everywhere.”

Should that prove the case, the FDA is still in the opening phases of establishing its approach to booster shots after Friday’s meeting, which could provide a general framework of how the agency will proceed with new iterations of the virus years from now. But there’s still some uncertainty lingering around the initial recommendation on boosters for people without compromised immune systems.

The FDA could theoretically overrule the advice of its independent experts as it has done on several infamous occasions, including when the agency green lit Biogen’s controversial Alzheimer’s treatment Aduhelm, and grant Pfizer a more wide-ranging authorization or approval. That would, however, be an extraordinary step in the context of a closely-watched pandemic and given the advisers’ recommendations for emergency use only in the high-risk and elderly. The Centers for Disease Control (CDC) will issue its own recommendations on booster dosing and prioritization next week. Pfizer rival Moderna is also hoping to win over regulators on a booster shot application, playing up data showing its own jab may be more effective than Pfizer’s against the Delta variant.

And, down the line, the science which feeds mRNA-based vaccines such as Pfizer’s and Moderna’s is malleable, suggesting companies will have plenty of opportunities to show hard, clinical data about how their respective vaccines and boosters fare against new strains. But the confounding factor will be balancing that dynamic science with the politics and psychology of a public health campaign.

For instance, the Biden administration stated that nearly every American adult should begin qualifying for booster shots by the end of September, a goal which now seems unlikely given the FDA panel’s limited recommendation. The White House’s original plan preempted any action taken by the FDA, leading to several prominent resignations at the agency over perceived political meddling in early September.

But it’s understandable to expect political pressure, especially as the current Delta variant wave is causing a massive spike in new cases and overwhelming hospitals, according to Gronvall. That’s just the reality of human nature.

“Early on with all of the COVID responses, whether it’s setting age limits for a vaccine, you had plenty of people who did not meet that age limit getting them,” she said. “It’s really hard to craft a policy where everybody’s going to fall into line like they’re inanimate objects without free will, or, you know, the power to kind of work the system.” It’s not a theoretical consideration, either. Many Americans have taken it upon themselves to secure booster shots despite being ineligible to do so, and at least 1 million people had already gotten an extra dose before any had been authorized by the FDA, according to CDC estimates.

For Gronvell, the more pressing matter is making sure the youngest Americans begin building immunity should the coronavirus become an endemic childhood disease that’s impossible to avoid. Depending on a child’s age and what dose of a vaccine they’re getting, COVID shots could buttress natural immunity from exposure to the virus without putting kids at risk for serious side effects.

But achieving that future will depend on establishing a foundation in the present by vaccinating as many people as possible, whether it be through boosters for those who need them or finally convincing unvaccinated people to get their shots. That, in turn, will depend on a comprehensive messaging strategy crafted in conjunction with the objective scientific data.

It’s not a simple needle for public officials to thread when crafting a nationwide narrative meant to encourage safe behavior when the science is far more nuanced.

“Do you really want to tell people,” said Gronvall, “at the same time that you’re trying to convince so many people that the vaccine is safe and effective, to say, ‘No, no, it’s not okay for you to get a third shot?'”