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Among the patients in the study who did not have measurable antibodies after receiving two doses of the vaccine, a third experienced a rise in antibodies after a third dose—and among those who had low antibody levels after two doses, all saw an increase after a third dose. The findings were published Monday in the Annals of Internal Medicine.
Organ transplant recipients may not have an adequate response to coronavirus vaccines because they are taking medications to suppress their immune system. This helps reduce the risk of the body rejecting new organs, but it may also limit responses to vaccines.
When it comes to coronavirus vaccines, “we don’t really have a good sense of the level you need for protective immunity,” Dr. Dore Segev, study author and founder of the Transplant Epidemiology Research Group at Johns Hopkins University, told CNN. “We don’t know if you need the same level of antibodies that is uncommon in people with normal immune systems.”
When drug companies tested coronavirus vaccines in clinical trials last year, they specifically excluded people who were taking immunosuppressive drugs because of the potential risks.
But for transplant patients, after a complete two-dose vaccine series, “the vast majority either have no antibodies or low antibodies,” Segev said.
Increased levels of antibodies
The researchers, from Johns Hopkins University School of Medicine in Baltimore, examined antibody responses and vaccine interactions in 30 transplant patients who received a third dose of the coronavirus vaccine between March and May of this year. Fifteen patients received a dose of the Johnson & Johnson vaccine, nine received the Moderna vaccine and six received Pfizer about 67 days after completing the second dose of the original vaccination.
The researchers tested the patients for antibodies before they received their third dose of the vaccine. They found that 24 patients had no detectable levels of antibodies and six had low levels.
The patients’ antibodies were tested again about two weeks after receiving a third dose of the vaccine. The researchers found that the six patients who previously had low antibody levels had higher antibody levels after the third dose. Of the patients who had no detectable level of antibodies, six had high levels, two had low levels, and 16 remained at an undetectable level after a third dose.
About a week later, 23 of the patients who completed a questionnaire about their reactions to the vaccine after receiving a third dose reported typical reactions such as pain at the injection site, fatigue, headache, or muscle aches.
In one recipient of a heart transplant, the researchers found some evidence of simple organ rejection a week after her third dose. But her heart function remained normal, and the rejection resolved without the need to ramp up her immunosuppressive system.
The researchers also noted that she had not seen an increase in antibodies and it was “uncertain” whether the mild rejection was associated with vaccination.
The new study comes about a month after Segev and his colleague published a paper in the medical journal JAMA that found that among 658 transplant recipients who received two doses of either the Pfizer or Moderna vaccine, nearly half did not respond to antibodies after two doses. They found that 15% had measurable antibody responses after the first and second dose and 39% had no antibody response after the first dose but a subsequent antibody response after the second.
Antibodies are not everything كل
Antibodies are just one part of the body’s immune response, so experts say future studies on enhancers should also measure the activities of other parts of the immune system outside of antibodies, such as T cells and B cells.
In April, health officials in France recommended a third dose of the vaccine for immunocompromised people. Segev said emergency use permits in the United States “restrict people to only a standard series of vaccines.” “And what happens is the transplant patients get the vaccine series, their antibodies get scanned, they realize it’s low, they talk to their doctors, and then they go and get a third dose to try to boost this.” Many medical communities, such as the American College of Rheumatology, the American Society For organ transplants, the International Organization for the Study of Inflammatory Bowel Disease, basically says that antibody tests will not fully answer patients’ questions about whether their vaccines are working, and the US Food and Drug Administration and the US Centers for Disease Control and Prevention advise against antibody testing, And the National Institutes of Health is beginning to identify methods that might work best if the vaccine fails people who are immune compromised. This summer, researchers hope to begin recruiting about 200 vaccinated kidney transplant patients to participate in a study on boosters, Dr. Daniel Rotrosin, director of NIAID’s Division of Allergy, Immunology, and Transplantation, told CNN earlier this month.
Rothrussen added that if tests show that the Covid-19 vaccine has not worked well, an additional dose of the vaccine will be given to the study participant to see if it helps. Segev and his colleagues will participate in this work.
“We hope over the next month or two to launch a clinical trial, which is an interventional trial, where we can give people third doses of the vaccine, and study the effect of that third dose in a very systematic way on the reaction of the immune system.” He added that the new study provides strong evidence that boosters will be beneficial in this group of patients.
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