COVID-19 vaccine offers minimal protection to organ transplant recipients: Study
Although two doses of a COVID-19 vaccine confer protection for people who have received solid organ transplants, it's not enough to enable them to dispense with masks, physical distancing, and safety measures, a study said. It's a follow-up study to an earlier one in which researchers reported, 17 percent of participating transplant recipients produced sufficient antibodies after one dose of a two-dose vaccine regimen.
Antibody levels increased, but not in enough transplant recipients
"There was an increase in those with detectable antibodies after the second shot," said lead author Brian Boyarsky from the Johns Hopkins University School of Medicine in the US. "However, the number of transplant recipients in our second study whose antibody levels reached high enough levels to ward off infection was still well below than in people with healthy immune systems," Boyarsky said.
Transplant recipients should continue to practice COVID-19 safety precautions
"Based on our findings, we recommend that transplant recipients and other immunocompromised patients continue to practice strict COVID-19 safety precautions, even after their vaccination," Boyarsky said. The researchers noted that the people who receive solid organ transplants, such as hearts, lungs, and kidneys, often must take drugs to suppress their immune systems and prevent rejection.
Some drugs affect transplant recipient's ability to make antibodies
"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," they said.
This immunogenic response after second dose was evaluated
The latest study, published in the Journal of the American Medical Association (JAMA), evaluated this immunogenic response following the second dose of either of the two 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 December 16, 2020, and March 13, 2021.
98 of 658 study participants had detectable antibodies
The researchers found that 98 of 658 study participants - 15 percent - had detectable antibodies to SARS-CoV-2 at 21 days after the first dose. This was comparable to 17 percent reported in the March study looking at immune response after only one vaccine dose.
Here are other figures regarding antibodies after vaccination
"At 29 days following the second dose, the number of participants with detectable antibodies rose to 357 out of 658 - 54 percent," the researchers said. "After both vaccine doses were administered, 301 out of 658 participants - 46 percent - had no detectable antibody at all while 259 - 39 percent - only produced antibodies after the second shot," they said.
Younger age group most likely to develop an antibody response
The researchers also found that among the participants, the most likely to develop an antibody response were mostly younger, those who did not take the immunosuppressive regimens including the anti-metabolite drugs and also received the Moderna vaccine. "These were similar to all the associations that were seen in the March single-dose study," the researchers said.
Wrong to assume two vaccine doses guarantee sufficient immunity
"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," said study co-author Dorry Segev, from the Johns Hopkins University School of Medicine.