Real-world protection from COVID-19 vaccination is better than expected in transplant recipients, reducing the risk of symptomatic infection by almost 80% in those who have had both doses compared with unvaccinated controls, a new transplant registry analysis shows.
“Persons who have received an organ transplant are considered to be at increased risk for COVID-19 and for a severe outcome because their immune systems are necessarily suppressed to ensure their transplants are successful and lasting,” lead author Saima Aslam, MD, professor of medicine, University of California, San Diego, said in a statement.
Because numerous studies have demonstrated reduced antibody responses to SARS-CoV-2 in solid organ transplant recipients and variable effect on T-cell responses, there has been a need to study clinical effectiveness and breakthrough infections in those who are vaccinated, they explained.
“These findings offer strong evidence that getting vaccinated provides significant protection,” Dr. Aslam noted.
The investigators say that recent data from France, as well as other studies, show an increased rate of detectable antibodies following a third dose of the Pfizer-BioNTech COVID-19 vaccine in organ transplant recipients, “but based on our data it is unclear if a third dose is clinically warranted.”
The researchers stressed that almost half of the solid organ transplant recipients analyzed in the study had not been vaccinated at all, even by the beginning of 2021 when the United States was well into a third wave of COVID-19 infections.
So there is still a significant need, the authors said, to continue to improve outreach efforts to those in the transplant community and promote the benefits of being fully vaccinated.
The study was published online recently in Transplant Infectious Disease.
Transplant registry
The researchers analyzed clinical data from the UC San Diego transplant registry from Jan. 1 through June 2 of this year, with 2,151 solid organ transplant recipients identified. The patients had received a variety of solid organ transplants including kidney, liver, lung, and heart; the largest percentage received a donor kidney.
Among all patients, 912 were fully vaccinated and 1,239 were not (1,151 of those 1,239 received no vaccine at all and 88 had been partially vaccinated; these 1,239 served as the control group).
Fully vaccinated patients had received two shots of either the Pfizer-BioNTech COVID-19 or the Moderna vaccine, or a single dose of the Johnson & Johnson vaccine. The majority, at nearly 70%, had received the Moderna vaccine. The mean age of the cohort was 57 years and the median time since patients had undergone transplantation was almost 5 years (57.5 months).
During the 6-month study interval, 65 cases of COVID-19 were documented in the group overall. Only 4 cases occurred among fully vaccinated individuals whereas 61 cases occurred among the unvaccinated, including in 2 patients who had been partially vaccinated.
Among the four cases that occurred among the fully vaccinated, two were considered mild and were treated on an outpatient basis, and the other two were moderate, requiring hospitalization and treatment with remdesivir.
There were no COVID-19–related deaths among the 4 patients who experienced breakthrough infections, whereas 2 (3.3%) of 61 of control patients died of COVID-19–related causes.
The authors noted that the incidence rate for COVID-19 was 0.065 per 1,000-person days among the fully vaccinated compared with an incidence rate of 0.34 per 1,000-person days in the control group.