The National Institutes of Health is giving a booster dose to 200 kidney transplant patients who did not have an immune response to the COVID-19 vaccine in a new trial that launched yesterday.
Many transplant patients, who have to take immunosuppressant drugs to keep their bodies from rejecting a new organ, don’t produce enough antibodies — or don’t produce antibodies at all — after getting the COVID-19 vaccine. The study will check to see if a third shot of an mRNA vaccine, given on top of the normal two-shot regimen, will generate antibodies closer to the levels seen in healthy people.
There are some indications that a third dose might help some people. In France, health officials started recommending in April that immunosuppressed patients get a third shot of the COVID-19 vaccine. Half of the patients who did not respond to two shots produced antibodies after the third, according to an analysis of 159 kidney transplant patients. The other half, though, still had no response. In Germany, one study of 48 transplant patients found that 40 percent who didn’t respond to two doses had a response after the third.
Two other trials looking at kidney transplant patients are also kicking off in Israel and Switzerland.
It’s possible that the existing body of research might be enough for health officials in the US to start recommending that immunocompromised patients get a third shot. The Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices will take up the question at its meeting on Friday.
Currently, COVID-19 vaccines are available under an emergency use authorization in the US that specifies two doses for the Pfizer / BioNTech and Moderna shots. In order for a third shot to become standard for any group, one of two things would have to happen: the Food and Drug Administration (FDA) would have to amend that authorization to include the option for an additional shot, or the agency would have to fully approve the vaccines. Once they’re approved, doctors could prescribe a third dose under a practice called off-label use, which lets doctors use pharmaceuticals based on their judgment even if they’re not technically cleared for a particular purpose.
Some people in the US are already skirting the FDA and seeking out third shots. More than 900 people have received a third shot in the US, according to data collected by the CDC, and it’s likely an undercount.