Extreme close-up photograph of gloved hand holding frost-covered glass vial.
Enlarge / A pharmacist holding a vial of the undiluted Pfizer-BioNTech vaccine for COVID-19.

The Food and Drug Administration is expected to announce Thursday (or soon after) that it is authorizing a third COVID-19 vaccine dose for some people with compromised immune systems, according to people familiar with the FDA’s plans.

The plans were first reported by NBC News and confirmed by CNN and Politico.

The FDA is expected to give a green light for a third dose of both the Moderna and Pfizer/BioNTech mRNA vaccines. The authorization for the third shots would come by way of updates to the vaccines’ emergency use authorizations.

Left out of the update is Johnson & Johnson’s one-shot COVID-19 vaccine. According to Politico’s sources, this is because federal officials believe very few immunocompromised people actually received the Johnson & Johnson vaccine. The shot was authorized well after immunocompromised people were initially eligible for vaccination and health care providers have since recommended that the immunocompromised seek the Moderna or Pfizer/BioNTech vaccines.

The third doses of the two mRNA vaccines are expected to help boost protection in the immunocompromised, which include cancer patients, organ-transplant patients, and people with HIV. Studies have found that people with compromised immune systems, including those taking immunosuppressive drugs, produce relatively poor immune responses after two standard doses—and that a third dose can help.

Boosted protection

Researchers published results Wednesday in The New England Journal of Medicine on a double-blind, randomized, controlled trial involving 120 organ-transplant recipients. The trial found that those who received a third dose of the Moderna vaccine had “substantially higher” levels of antibody and virus neutralization than the placebo group, which had only received two doses. Likewise, a smaller study published last month in the Annals of Internal Medicine found that a third vaccine dose could produce an antibody response even in some transplant recipients who had no detectable antibody levels after the second dose.

For now, it’s unclear which groups of immunocompromised patients will be authorized to receive a third dose. An estimated 7 million adults in the US are immunocompromised overall.

“We’ve been concerned about these [immunocompromised] individuals,” Surgeon General Vivek Murthy said Wednesday afternoon on CNN. “The FDA has been working hard to basically do the evaluation around safety, make sure that we have everything we need to make these additional doses available to people. The CDC is also looking into making sure that guidance is clear and available for immunocompromised individuals.”

Once the FDA authorizes the change, a committee of expert advisors for the Centers for Disease Control and Prevention will set official federal recommendations for administering the third doses. That committee—the Advisory Committee on Immunization Practices (ACIP)—has already planned a meeting for this Friday, August 13, in which committee members will discuss additional doses of COVID-19 vaccines for immunocompromised individuals.

The World Health Organization has called for a temporary moratorium on COVID-19 booster shots, but it has said that the moratorium does not apply to necessary extra doses for immunocompromised people.