Are live vaccines safe in pediatric liver recipients?
With a resurgent of measles, which carries up to a 70% mortality rate in immunocompromised children, some experts wonder if the historical recommendation that the MMR and varicella (VZV) vaccines should not be administered to solid organ transplant recipients is still justified. During a presentation at the 2021 SPLIT Annual Meeting, Amy Feldman, MD discussed recent studies exploring the safety and efficacy of live vaccines in liver transplant recipients.
After a small prospective study on live vaccines administered post-liver transplant found no serious systemic adverse events in any patients studied, an international group of experts reviewed all the current literature on the topic. They concluded that live vaccines safe and should be considered in patients at least 1-year post-liver transplant and 2 months post-rejection; on low dose immunosuppression, and with essentially a normal immune system.
Dr Feldman is involved in the SPLIT-PIDS joint prospective observation study of live vaccines and shared preliminary data during her presentation. Of the 106 patients enrolled, 72 received the MMR vaccination and 86 received the VZV vaccination.
The median age at transplant was 11.8 months and the median age at post-transplant vaccination was 8.3 years. Most patients (n = 100) were on tacrolimus.
After 1-3 doses of VZV, 56% of patients had positive VZV IgG. After 1-3 doses of MMR, 60% had positive measles IgG, positive mumps IgG, and 52% had positive rubella IgG.
Although these numbers are low, Dr Feldman said she expects that these numbers will rise as the study goes on.
Side effects included:
-2 children with biopsy-proven rejection after 1st VZV/MM
-3 children with VZV
-20 with nonserious adverse events
In addition to live vaccines, Dr Feldman also briefly discussed the COVID-19 vaccine, which all major organ transplant organizations recommend, and recent studies exploring its safety and efficacy in solid organ transplant recipients.
Although not as effective as in the healthy population, a small study of 658 transplant recipients found that 15% had antibodies after the first dose and 54% after 2nd dose. Liver transplant recipients were found to have a better response than other solid organ transplant recipients. Another study of 396 transplant recipients found that 68% had antibodies after a 3rd dose.
A study including 52 pediatric solid organ transplant recipients reported that of the 45 participants who had antibodies measured after the 2nd dose, 73% had positive antibodies. No serious adverse events were noted.
Predictors of a negative response included a transplant within 3 years, on multiple immunosuppression agents, and on antimetabolite.
Feldman A. An Update on Vaccines for the Pediatric Liver Transplant Population. Presented at: 2021 SPLIT Annual Meeting.