Do transplant patients need a third vaccine dose? A new Toronto-based study has the answer

TORONTO -

After two doses of the Moderna vaccine, Mike Willis said he had zero antibodies to combat COVID-19. More than five years ago, the 66-year-old received a heart transplant and has been immunocompromised ever since.

But now, after receiving a third dose of Moderna, he has developed some antibodies. “Some is definitely better than none,” Willis said.

Willis was one of 120 transplant patients enrolled in the first study in the country to determine that a vaccine booster is “very effective” in transplant patients, published on Wednesday in the New England Journal of Medicine.

“It’s really the first study that has really shown the benefit of third doses,” said Dr. Deepali Kumar, director of transplant infectious diseases at Toronto’s University Health Network and joint-senior author of the study with Dr. Atul Humar.

Previous research has found that transplant patients have an “undoubtedly” higher mortality rate due to COVID-19, compared to the general population. In essence, two doses was not enough to produce coronavirus-fighting antibodies.

This study was the first-in-the-world to conduct a randomized placebo-controlled trial on the subject — deemed the “gold standard” in medicine. The relevance of this highly-esteemed classification is it proves the results are conclusive and truly effective.

Patients were divided into groups, both had previously received two doses of a COVID-19 vaccine, but some received a third placebo dose, while others got a third dose of Moderna. After two doses of Moderna and one placebo dose, only 18 per cent of people had a sufficient antibody level that could combat the virus. The group that received a third dose of Moderna had a 55 per cent response rate.

“This is a highly significant number,” Dr. Kumar said.

Dr. Deepali Kumar and Dr. Atul Humar are the joint-senior authors of a new study that shows the effectiveness of vaccine booster shots for transplant patients.

The study found the third dose only resulted in mild side effects and it did not cause organ rejection in transplant patients, which has been a significant concern in the transplant community.

Typically, studies of this nature would take at least a year, but Dr. Kumar’s team produced the results in a matter of months.

Now, she is asking policymakers to do the same, hoping for an expedited approval process for third doses for transplant patients. “We need to move rapidly,” she said. “With the Delta variant, I think we need to do whatever we can to protect immunocompromised patients.”

The study’s results have been shared with the Food and Drug Administration, the Canadian National Advisory Committee on Immunization and the American Society of Transplantation.

“It’s opening the door to a lot more than just third doses in transplant recipients,” Dr. Kumar said. “I think it’s opening the door to other immunocompromised groups as well.”