Federal officials are looking to authorize additional Covid-19 doses for people with weakened immune systems amid recommendations from public health officials, including Anthony Fauci—but some experts still advise caution against providing booster doses too soon.

Your top resources on the Covid-19 vaccines

A rising interest in boosters

According to the New York Times, as the highly contagious delta variant leads to surges in Covid-19 cases across the country and reports of breakthrough infections among the vaccinated rise, many people are interested in getting "booster" doses of the Covid-19 vaccines.

Radio Advisory episode: Vaccinating the globe, the ultimate systemness challenge

Some countries, such as the United Kingdom, France, Israel, and Germany, have already begun giving additional doses to certain groups, such as older adults and those who are immunocompromised. And in the United States, San Francisco last week announced it would allow patients who received Johnson & Johnson's Covid-19 vaccine to receive a "supplemental" dose of either Pfizer-BioNTech or Moderna's vaccine.

However, the World Health Organization last week called for a moratorium on Covid-19 booster shots—except in cases where someone is not already protected by a full vaccine regimen—until at least 10% of every country's population is fully vaccinated.

Additional shots recommended for certain groups

Federal officials are moving quickly to recommend additional Covid-19 vaccine doses for Americans with compromised immune systems, the Washington Post reported on Friday. The additional doses are expected to be authorized within a few days or weeks.

Specifically, according to the Post, FDA in the coming week or two is expected to review CDC data on the benefits of additional vaccine doses for immunocompromised individuals.

If FDA finds the data compelling, the agency could amend its current emergency use authorizations for Covid-19 vaccines to permit extra doses. This amendment would allow certain patients to get an additional vaccine dose legally instead of seeking them out on their own, which experts worry could be unsafe. 

Around 7 million adults in the United States are immunocompromised, according to CDC, and they are more likely to become seriously ill from Covid-19 and may spread the coronavirus more frequently compared to others.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical advisor to the White House, echoed those sentiments on Sunday, saying that while it's likely people will eventually need booster shots, currently only those who are older or have weakened immune systems should be considered for a supplemental dose—not otherwise healthy, fully vaccinated adults.  

The most promising Covid-19 drugs in development—beyond vaccines

"It is extremely important for us to move to get those [who are immunocompromised] their boosters, and we are working on that now," Fauci said on Thursday. He added that many people who are immunocompromised do not have an immune response that "would be adequately protective."

Some experts still advise caution

According to STAT News, some public health experts and health officials have cautioned against booster shots—both for otherwise healthy, fully vaccinated adults and for those with weakened immune systems—until more information is known.  

For example, Kate O'Brien, WHO's director of immunization, vaccination, and biologics, said it is ill-advised to provide booster shots without strong evidence that they are needed. "If we're not really grounded in that clarity, we're going to be in a place where we have forever uncertainty about what actually should be done," O'Brien said.

In addition, according to the New York Times, it is still unclear whether additional vaccine doses will in fact be beneficial to people with weak immune systems. A study published in the Annals of Internal Medicine found that only a third of organ transplant recipients improved their immune response after a third Covid-19 dose.

There are also potential safety concerns for patients whose immune responses have been suppressed purposefully. For example, according to Dorry Segev, a transplant surgeon at Johns Hopkins University and one of the authors of the organ transplant study, a patient in that study experienced mild rejection of her transplanted heart, although she later recovered. Patients with autoimmune conditions may also experience issues when their immunity is enhanced, he said.

Currently, there is no long-term data on people who have received extra doses. "I don't think there is strong evidence that a third dose is safe yet—there is encouraging evidence," Segev said.

In the meantime, Segev recommends people who are immunocompromised and want an extra vaccine dose to enroll in research studies that will closely monitor their responses to the shot. (Gounder et al., New York Times, 8/9; Choi, The Hill, 8/8; Weise/Weintraub, USA Today, 8/8; McGinley et al., Washington Post, 8/6; Mandavilli/LaFraniere, New York Times, 8/9; Branswell, STAT News, 8/9)