Despite being fully vaccinated, transplant recipients remain at greater risk for COVID-19
After a second dose of either the Moderna or Pfizer-BioNTech COVID-19 vaccine, solid organ transplant recipients failed to achieve an antibody response against SARS-CoV-2 comparable to the general population.
According to a related press release, this study continues research that the team from Johns Hopkins School of Medicine conducted earlier in 2021, which showed 17% of transplant recipients “produced sufficient antibodies” after one dose of the two-dose regimen.
“While there was an increase in those with detectable antibodies — 54% overall — after the second shot, the number of transplant recipients in our 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,” Brian J. Boyarsky, MD, PhD, said in the release. “Based on our findings, we recommend that transplant recipients and other immunocompromised patients continue to practice strict COVID-19 safety precautions, even after vaccination.”
For the study, Boyarsky and colleagues included 658 transplant recipients who completed a two-dose vaccine regimen between December 2020 and March 2021.
Researchers found the first dose led to a detectable antibody response in 15% of transplant recipients; the response occurred at a median of 21 days after the first dose was administered. After the second dose, an antibody response was detectable in 54% of participants, occurring a median of 29 days later (46% had no response after either dose).
“Although no threshold has been established for protective immunity, antibody levels were well below that which has been observed in immunocompetent vaccinees,” the researchers wrote, noting that median antibody levels after the second dose were 2.14 U/mL for all participants (including those with no response) and were 142.1 U/mL for those who had detectable antibody levels after the second dose.
Participants who received the Moderna vaccine were more likely to develop an antibody response than were those who received the vaccine from Pfizer-BioNTech, results suggested.
Co-investigator on the study Dorry Segev, MD, PhD, also commented on the findings in the release, advising: “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.”