How Could FDA’s New Guidance Affect COVID-19 Vaccination Coverage in the U.S.?

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On Tuesday, the Food and Drug Administration (FDA) announced new guidance about the evidence it will require to approve COVID-19 vaccines in some cases. Specifically, the FDA says that to approve new or updated COVID-19 vaccines (“boosters”) for use in individuals who are not considered at higher risk (higher risk is defined as persons 65 or older or those with certain health conditions), vaccine makers will need to present evidence from randomized, placebo-controlled trials that demonstrate safety and efficacy. This is a departure from past years, when FDA did not require new randomized controlled trial data to authorize or approve boosters but instead allowed evidence of immune response to be used.

As part of its announcement, FDA leadership noted that the U.S. has been more aggressive than peer nations in recommending COVID-19 vaccines for all ages every year, suggesting that HHS will seek to align U.S. policy with Canada, Australia, and countries in Europe (though these countries have not explicitly imposed the same kind of clinical trial requirements for boosters that the FDA now has). Indeed, the newly announced guidance and potential shift in recommendations also come on the heels of FDA’s conditional approval of a new COVID-19 vaccine from Novavax after an extended and contested regulatory review. In contrast to COVID-19 vaccines from Pfizer and Moderna that were authorized and approved for use in anyone over 6 months of age (based on the earlier, original controlled clinical trials for those vaccines), the Novavax vaccine has been approved for use only in persons over the age of 65 or those between the ages of 12 and 64 with an underlying condition that puts them at higher risk for severe outcomes from COVID-19 infection. In addition, FDA’s approval requires Novavax to conduct a new, post-approval, randomized, placebo-controlled trial in individuals aged 50 through 64 without high-risk conditions for severe COVID-19. This requirement is in line with Tuesday’s announcement from FDA about clinical trial requirements for COVID-19 vaccines.

There could be even more changes to federal COVID-19 vaccine guidance emerging in the coming weeks. FDA’s external vaccine advisory committee, known as VRBPAC, will convene on May 22 to discuss and vote on recommendations for the 2025-2026 COVID-19 booster vaccine formula, a meeting that takes place now in the context of this new guidance. Next month, CDC’s external vaccine advisory committee, known as ACIP, will meet to provide public health recommendations about the use of COVID-19 vaccines for the coming year, and the committee is considering limiting its recommendations for COVID-19 boosters to persons 65 or older and those at higher risk of severe disease. In the end, however, VRBPAC and ACIP recommendations are only that —recommendations. Final approval decisions and federal guidance on the use of COVID-19 boosters will come from the FDA and CDC, and ultimately HHS Secretary Robert F. Kennedy. According to reports, Kennedy has been considering ending recommendations that children receive COVID-19 boosters, a stance that seems reflected in the policy moves made by FDA so far.

Taken together, the new guidance on clinical trial requirements, the more restricted approval of the Novavax vaccine, and anticipated changes to CDC recommendations add up to fewer Americans eligible for COVID-19 vaccines and more limited access to these vaccines compared to previous years. However, as noted above, such a shift would place the U.S. more in line with Australia, Canada, and countries in Europe.

Even though these changes would mean U.S. policies resemble peer nations more closely, they could also reduce incentives for companies, including Pfizer and Moderna, to invest in updated COVID-19 vaccines, given that they now face higher evidence requirements, greater costs, and longer time frames associated with conducting new randomized clinical trials.

More broadly, all of this is taking place when COVID-19 vaccine uptake in the U.S. is relatively low, and public opinion on the safety of these vaccines is just as divided as ever, particularly along partisan lines. According to CDC, during the last winter season COVID-19 booster vaccination rates among adults (18+) reached only about 23%, and even among those 65 and older, just about 44% received a booster shot. This was much lower than the 72% of those 65 and older who received a seasonal influenza vaccine. On public opinion, KFF polling from April of this year found that only around half of adults said they are at least “somewhat confident” the existing COVID-19 vaccines are safe, which included nearly nine in ten Democrats (87%), about half of independents (55%), but just three in ten Republicans. These results show much lower confidence in COVID-19 vaccines compared to other routine adult vaccines. Notably, the FDA has said one of the outcomes it hopes to see from its new evidence requirements is greater trust in COVID-19 vaccines, and vaccines more generally. This represents a big bet, as it remains to be seen whether these changes, which actually restrict options and place more limits on access to vaccines, will reverse the current trend of growing distrust of vaccinations in the U.S., and lead to more vulnerable people being vaccinated against COVID-19.