Transplant Recipients Prone to COVID-19 Even After Second Dose

Johns Hopkins Medicine researchers urge people who are immunocompromised to strictly follow COVID-19 safety measures, even after vaccination

Two doses of COVID-19 vaccine may not confer protection for people who have received solid organ transplants, as per the study published in the Journal of the American Medical Association (JAMA).

This is a follow-up study to an earlier one published in JAMA, in which the researchers reported that only 17% of the participating transplant recipients produced sufficient antibodies after just one dose of a two-dose COVID-19 vaccine regimen.

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"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," says study lead author Brian Boyarsky, M.D., a surgery resident at the Johns Hopkins University School of Medicine.

"Based on our findings, we recommend that transplant recipients and other immunocompromised patients continue to practice strict COVID-19 safety precautions, even after vaccination," Boyarsky says.

Solid organ transplants (such as hearts, lungs and kidneys) recipients must take drugs to suppress their immune systems and prevent rejection. These drugs may interfere with a transplant recipient's ability to make antibodies to foreign substances, including the protective ones produced in response to vaccines.

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

Only 98 of the 658 participants 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 one vaccine dose.

Number of participants with detectable antibodies rose to 357 out of 658. After both vaccine doses were administered, 301 out of 658 participants had no detectable antibody at all while 259 only produced antibodies after the second shot.

Among the participants, the most likely to develop an antibody response were younger, did not take immunosuppressive regimens including anti-metabolite drugs and received the Moderna vaccine. These were similar to the associations seen in the March single-dose study.

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"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 one dose," says study co-author Dorry Segev, M.D., Ph.D., 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.

Segev says 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.

Source-Medindia