A third dose of an mRNA COVID-19 vaccine provided immunocompromised organ transplant patients with “substantially” improved protection, according to a trial published in The New England Journal of Medicine.
To keep the body from rejecting transplanted organs, patients must take medications that suppress the immune system.
Previous studies have shown that two doses of the vaccines were not enough to produce good immune responses in these patients. In the new trial, researchers found that 60% of patients who were given a third dose of the Moderna mRNA vaccine developed antibodies that could neutralize the virus, compared to only 25% of the placebo group.
The extra dose, which was administered two months after the second dose, was well tolerated with mostly mild side effects, and it also prompted substantial improvement in patients’ T-cell responses, another aspect of immunity.
The results “quite convincingly” suggest that a third shot is worthwhile for transplant patients, said coauthor Dr. Atul Humar of the University Health Network in Toronto.
On Thursday, the U.S. Food and Drug Administration authorized vaccine boosters from Pfizer/BioNTech and Moderna for people with compromised immune systems.