COVID-19 Boosters Get FDA EUA For All US Adults: When To Get Your Shot

The FDA has given the green light for Moderna and Pfizer-BioNTech COVID-19 vaccine booster shots for adults, updating the emergency use authorization as the US settles in for an extended pandemic. The amended EUA allows for a single extra dose of vaccine for those aged 18 years or older, after they have completed their primary vaccination with any other FDA-authorized or approved drug.

The expansion opens the doors to widespread booster shots around the US, building on the existing authorization for certain at-risk categories. That included all individuals 65 years of age or older, those 18 to 64 with high risk of severe COVID-19, and those in the same age bracket who faced "frequent institutional or occupational exposure" to the coronavirus, such as from working in healthcare settings.

That only came after an initial push to expand booster eligibility to all in the US aged 18 or older. The FDA tempered that ambition earlier this year, following reticence by its guiding body to recommend such a widespread change to the EUA. Now, though, with COVID-19 cases climbing again in many states, and the threat of comorbidity with flu during the winter, a more aggressive stance has been adopted.

"Authorizing the use of a single booster dose of either the Moderna or Pfizer-BioNTech COVID-19 vaccine for individuals 18 years of age and older helps to provide continued protection against COVID-19, including the serious consequences that can occur, such as hospitalization and death," Janet Woodcock, M.D., the Acting FDA Commissioner said today in a statement.

The booster shot is open to anybody in the US in the 18+ age bracket, regardless of whether they had the Moderna, Pfizer, or Janssen one-shot vaccines originally. For the first two, the booster should be given at least six months after the second injection of the primary course of vaccination. For Janssen's single-dose vaccine, meanwhile, the booster can be given after at least two months of that dose.

The FDA – and the Biden Administration – had been criticized from some quarters for the potential for confusion in the booster roll-out. In particular, the intentionally vague criteria for those in "at risk" groups was singled out as being counter-intuitive for a simple public health message.

That appears to have been a motivating factor – in addition to the research – for the FDA's announcement today. "Streamlining the eligibility criteria and making booster doses available to all individuals 18 years of age and older will also help to eliminate confusion about who may receive a booster dose and ensure booster doses are available to all who may need one," Peter Marks, M.D., Ph.D., director of the FDA's Center for Biologics Evaluation and Research, said in a statement.

As for that data, for Moderna's vaccine the FDA looked at immune response data from 149 participants who had received a booster shot, and compared it to more than a thousand who only had the initial two shots. Antibody response – that is to say, the body's ability to fight off COVID-19 infection – was higher in the booster group when measured 29 days after it had been administered.

Similarly, for Pfizer-BioNTech's vaccine, the FDA looked at approximately 200 participants who received a single booster shot six months after their primary vaccination course. Again, a month following that booster, it was found that the group had a stronger antibody response than those who did not receive a booster.

Next will come a meeting by the Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices, expected to take place later today. That will add clinical recommendations – in short, the roll-out plan for widespread boosters – to the FDA's authorizations.