Organ transplant recipients might not have an adequate response to coronavirus vaccines because they take drugs to suppress their immune systems. That helps reduce the risk of the body rejecting new organs but may also limit responses to vaccines.
When pharmaceutical companies tested coronavirus vaccines in clinical trials last year, they specifically excluded people who were taking immunosuppressive drugs due to potential risks.
But for transplant patients, after a two-dose full vaccine series, “the overwhelming majority have either no antibodies or low antibodies,” Segev said.
Boosting antibody levels
The researchers, from the Johns Hopkins University School of Medicine in Baltimore, examined antibody responses and vaccine reactions in 30 organ transplant patients who received a third dose of coronavirus vaccine between March and May of this year. Fifteen patients received a dose of the Johnson & Johnson vaccine, nine received Moderna’s shot and six received Pfizer’s around 67 days after completing the second dose of their original vaccination.
The researchers tested the patients for antibodies before they received their third doses of vaccine. They found 24 patients had no detectable antibody levels and six had low levels.
The patients were tested for antibodies again about two weeks after receiving a third dose of vaccine. The researchers found that the six patients who previously had low antibody levels all had high antibody levels after their third dose. Among the patients with no detectable level of antibodies, six had high levels, two had low levels and 16 remained at a 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 pain.
In one heart transplant recipient, there was some evidence of mild organ rejection a week after her third dose, the researchers found. But her heart function remained normal, and the rejection resolved without needing to intensify her immunosuppressive regimen.
The researchers also noted that she did not experience an increase in antibodies and “it is uncertain” whether the one case of mild rejection was related to vaccination.