Study Finds Organ Transplant Recipients Remain Vulnerable to COVID-19 Even After Second Vaccine Dose

A new Johns Hopkins Medicine study shows that although 2 doses of a vaccine against SARS-CoV-2 confers some protection for people who have received solid organ transplants, it is not enough to enable them to dispense with masks, physical distancing, and other safety measures.

The research is a follow-up to a previous study published in March in which the researchers reported that only 17% of participating transplant recipients produced sufficient antibodies after just 1 dose of a 2-dose COVID-19 vaccine regimen.

“While there was an increase in those with detectable antibodies- 54% overall- after the second shot, the number of transplant recipients in our second study whose antibody levels reached high enough levels to ward off a SARS-CoV-2 infection was still well below what’s typically seen in people with healthy immune systems,” said study lead author Brian Boyarsky, MD, a surgery resident at the Johns Hopkins University School of Medicine, in a press release. “Based on our findings, we recommend that transplant recipients and other immunocompromised patients continue to practice strict COVID-19 safety precautions, even after vaccination.”

The new study evaluated this immunogenic response following the second dose of either of the 2 messenger RNA (mRNA) vaccines, made by Moderna and Pfizer-BioNTech, for 658 transplant recipients, none of whom had a prior diagnosis of COVID-19. The participants completed their 2-dose regimen between December 16, 2020, and March 13, 2021.

In the most recent study, the researchers found that only 15% had detectable antibodies to SARS-CoV-2 at 21 days after the first vaccine dose. This was comparable to the 17% reported in the March study looking at immune response after only 1 vaccine dose, according to the study.

At 29 days following the second dose, the number of participants with detectable antibodies rose to 54%. After both vaccine doses were administered, 46% had no detectable antibody at all, whereas 39% only produced antibodies after the second shot.

Additionally, the researchers found that among the participants, the most likely to develop an antibody response were younger patients who did not take immunosuppressive regimens including anti-metabolite drugs, and who received the Moderna vaccine. These were similar to the associations seen in the March single-dose study, according to the study authors.

“Given these observations, transplant recipients should not assume that two vaccine doses guarantee sufficient immunity against SARS-CoV-2 any more than it did after just 1 dose,” said study co-author Dorry Segev, MD, PhD, the Marjory K. and Thomas Pozefsky Professor of Surgery and Epidemiology and director of the Epidemiology Research Group in Organ Transplantation at the Johns Hopkins University School of Medicine, in the press release.

Segev notes that future studies should seek to improve COVID-19 vaccine responses in this population, including additional booster doses or modulating the use of immunosuppressive medications so that sufficient antibody levels are achieved.

REFERENCE

Organ transplant recipients remain vulnerable to COVID-19 even after second vaccine dose. Johns Hopkins Medicine. Published May 5, 2021. Accessed May 7, 2021. https://www.hopkinsmedicine.org/news/newsroom/news-releases/organ-transplant-recipients-remain-vulnerable-to-covid-19-even-after-second-vaccine-dose