Live viral vaccines safe for pediatric solid organ transplant recipients

1. This cohort study of pediatric solid organ transplant (SOT) patients found that the measles-mumps-rubella (MMR) and varicella-zoster virus (VZV) vaccines were both safe and efficacious, with low risk for serious adverse events and infection. 

Evidence Rating Level: 2 (Good)

In SOT recipients, no recommendation to date has supported the use of live vaccines (MMR and VZV) due to theoretical risk of infection. This immunocompromised population, particularly the pediatric subgroup, is left susceptible to these life-threatening conditions and faces unique challenges in safeguarding their own health. With the rising rates of measles, mumps, and varicella worldwide, there is a role for determining whether these vaccines are able to provide robust protection without compromising safety in this vulnerable group. The current cohort study sought to explore this very topic. A total of 281 kidney or liver transplant patients (270 liver, 9 kidney, 2 liver-kidney recipients) who had not fully completed their MMR and VZV vaccine series and/or displayed nonprotective serum antibodies were selected. Most patients were receiving low level immunosuppression (although some were receiving more extensive immunosuppression), were more than 1 year post transplant and two months post rejection, and were assessed to have age-appropriate lymphocyte counts. Patients received between 1-3 doses of MMR, VZV, or both vaccines. In posttransplant participants, when tested for protective antibodies between one to three months post-vaccination, 72% developed protective antibodies for VZV, 86% developed protective antibodies for measles, and 99% developed protective antibodies for mumps. One-year post-vaccination, protective antibodies were maintained in the majority of recipients. Following VZV vaccination, 5 of the 217 children (2%; all receiving moderate to high immunosuppression at the time) developed clinical varicella more than one-week post-vaccine, all with resolution within 1 week (three of the five required antiviral therapy). No measles or rubella cases were recorded, and although one patient experienced transient nontender subauricular lymph node swelling without other symptoms 3 weeks after MMR vaccination, this resolved without intervention. With respect to safety, there were no serious adverse events recorded. The results above indicate that, in this study, live vaccinations post-transplant were both safe and immunogenic. While these preliminary results are promising and could signal a shift in recommendations for live vaccination in this population, further studies should be repeated and elucidate the associations between pretransplant antibody levels/vaccination and findings post-transplant. Other types of organ transplant should also be considered in future studies.

Click to read the study in JAMA Network Open

Image: PD

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