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Not much has been said about the effectiveness of COVID-19 vaccine in organ transplant recipients. This group of people are immunocompromised and very vulnerable. Now a new study from Johns Hopkins University School of Medicine say that although two doses of a vaccine against the virus that causes COVID 19 offers some protection for people who have received solid organ transplants, it is still not enough to enable them to dispense with masks, physical distancing and other safety measures. The Journal of the American Medical Association (JAMA) published this study. This is a follow-up study to an earlier one published in March in JAMA, in which the researchers reported that only 17 per cent of the participating transplant recipients produced sufficient antibodies after just one dose of a two-dose COVID-19 vaccine regimen.
Researchers say that while there was an increase in those with detectable antibodies 54 per cent overall -- after the second shot, the number of transplant recipients in the 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. This seems to suggest that organ transplant recipients may not be as protected by the COVID-19 vaccine as the general population.
Based on these findings, researchers recommend that transplant recipients and other immunocompromised patients continue to practice strict COVID-19 safety precautions, even after vaccination. People who receive solid organ transplants (such as hearts, lungs and kidneys) often must take drugs to suppress their immune systems and prevent rejection. Such regimens may interfere with a transplant recipient's ability to make antibodies to foreign substances, including the protective ones produced in response to vaccines.
The new study evaluated this immunogenic response following the second dose of either of the two 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 two-dose regimen between Dec. 16, 2020, and March 13, 2021. In the most recent study, the researchers found that only 98 of the 658 study participants 15 per cent -- had detectable antibodies to SARS-CoV-2 at 21 days after the first vaccine dose. This was comparable to the 17 per cent reported in the March study looking at immune response after only one vaccine dose. At 29 days following the second dose, the number of participants with detectable antibodies rose to 357 out of 658 54 per cent. After both vaccine doses were administered, 301 out of 658 participants 46 per cent -- had no detectable antibody at all while 259 39 per cent -- only produced antibodies after the second shot.
The researchers also found that 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. Hence, researchers say that transplant recipients should not assume that two vaccine doses guarantee sufficient immunity against the COVID-19 virus any more than it did after just one dose.
(With inputs from Agencies)
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