Safety and Immunogenicity of Live Viral Vaccines in a Multicenter Cohort of Pediatric Transplant Recipients

Importance

Live vaccines (measles-mumps-rubella [MMR] and varicella-zoster virus [VZV]) have not been recommended after solid organ transplant due to concern for inciting vaccine strain infection in an immunocompromised host. However, the rates of measles, mumps, and varicella are rising nationally and internationally, leaving susceptible immunocompromised children at risk for life-threating conditions.

Objective

To determine the safety and immunogenicity of live vaccines in pediatric liver and kidney transplant recipients.

Design, Setting, and Participants

This cohort study included select pediatric liver and kidney transplant recipients who had not completed their primary MMR and VZV vaccine series and/or who displayed nonprotective serum antibody levels at enrollment between January 1, 2002, and February 28, 2023. Eligibility for live vaccine was determined by individual US pediatric solid organ transplant center protocols.

Exposures

Exposure was defined as receipt of a posttransplant live vaccine. Transplant recipients received 1 to 3 doses of MMR vaccine and/or 1 to 3 doses of VZV vaccine.

Main Outcome and Measure

Safety data were collected following each vaccination, and antibody levels were obtained at 0 to 3 months and 1 year following vaccination. Comparisons were performed using Mann-Whitney U test, and factors associated with development of postvaccination protective antibodies were explored using univariate analysis.

Results

The cohort included 281 children (270 [96%] liver, 9 [3%] kidney, 2 [1%] liver-kidney recipients) from 18 centers. The median time from transplant to enrollment was 6.3 years (IQR, 3.4-11.1 years). The median age at first posttransplant vaccine was 8.9 years (IQR, 4.7-13.8 years). A total of 202 of 275 (73%) children were receiving low-level monotherapy immunosuppression at the time of vaccination. The majority of children developed protective antibodies following vaccination (107 of 149 [72%] varicella, 130 of 152 [86%] measles, 100 of 120 [83%] mumps, and 124 of 125 [99%] rubella). One year post vaccination, the majority of children who initially mounted protective antibodies maintained this protection (34 of 44 [77%] varicella, 45 of 49 [92%] measles, 35 of 42 [83%] mumps, 51 of 54 [94%] rubella). Five children developed clinical varicella, all of which resolved within 1 week. There were no cases of measles or rubella and no episodes of graft rejection within 1 month of vaccination. There was no association between antibody response and immunosuppression level at the time of vaccination.

Conclusions and Relevance

The findings suggest that live vaccinations may be safe and immunogenic after solid organ transplant in select pediatric recipients and can offer protection against circulating measles, mumps, and varicella.

Survey of pediatric transplant center practices regarding COVID-19 vaccine mandates for transplant candidates and living donors and use of COVID-19-positive deceased organs

BACKGROUND

COVID-19 vaccine is recommended for individuals ages ≥6 months; however, whether vaccination should be mandated for transplant candidates and living donors remains controversial. This study assessed COVID-19 policies at US pediatric solid organ transplant centers.

METHODS

A 79-item survey was emailed between March and April 2022 to 200 UNOS Medical Directors detailing center COVID-19 vaccine policies for transplant candidates and living donors and use of grafts from COVID-19-positive deceased donors.

RESULTS

The response rate was 77% (154/200). For children aged 5-15 years, 23% (35/154 centers) have a COVID-19 vaccine mandate, 27% (42/154) anticipate implementing a future mandate, and 47% (72/154) have not considered or do not anticipate implementing a mandate. For children ≥16 years, 32% (50/154 centers) have a COVID-19 vaccine mandate, 25% (39/154) anticipate implementing a future mandate, and 40% (62/154) have not considered or do not anticipate implementing a mandate. The top two reasons for not implementing a COVID-19 vaccine mandate were concerns about penalizing a child for their parent's decision and worsening inequities in transplant. Of 85 kidney and liver living donor centers, 32% (27/85) require vaccination of donors. Twenty percent (31/154) of centers accept organs from COVID-19-positive deceased donors.

CONCLUSIONS

There is great variation among pediatric SOT centers in both the implementation and details of COVID-19 vaccine mandates for candidates and living donors. To guide more uniform policies, further data are needed on COVID-19 disease, vaccine efficacy, and use of grafts from donors positive for COVID-19 in the pediatric transplant population.

Successful non-directed living liver donor transplant for an infant with biliary atresia during the COVID-19 pandemic

Amidst the coronavirus (COVID-19) pandemic, the American Society for Transplant Surgeons has recommended that only urgent liver transplant with deceased donors should occur. However, young pediatric candidates rely on living donors for lifesaving transplant. We present a case of non-directed left lateral lobe living liver donor transplant for a 7-month-old child with biliary atresia experiencing repeated life-threatening episodes of sepsis and cholangitis from infected bile lakes. Using careful preoperative planning among the entire multidisciplinary team, paying meticulous attention to infection control pre- and post-operatively, and taking advantage of robust telehealth technology both in and out of the hospital, a successful transplant was achieved. Amidst the COVID pandemic, non-directed liver transplantation can be safely achieved for pediatric recipients.