Expanding Access to Live Viral Vaccines for Pediatric Liver Transplant Candidates

Research study background

As measles and mumps infections surge in the United States and across the globe, children with chronic liver disease (CLD) are increasingly vulnerable to these life-threatening, vaccine-preventable diseases. A new study suggests young liver transplant candidates can safely receive live viral vaccines up to two weeks before transplantation.

Current guidelines call for a four-week waiting period after measles, mumps, rubella (MMR) and varicella-zoster virus (VZV), also known as chicken pox, vaccinations to allow time to clear the virus and prevent vaccine-strain disease post-transplant. The waiting period has resulted in many children with CLD not receiving live viral vaccines, or having their transplant delayed with possible missed opportunities to use excellent grafts.

This two-site prospective study, led by a multidisciplinary team of researchers at Children’s Hospital Colorado, was published in the American Journal of Transplantation. The team included Children’s Colorado hepatologist Amy Feldman, MD, PhD, former Children’s Colorado liver transplant fellow Sarah Kemme, MD, infectious disease expert Adriana Weinberg, and researchers Jennifer Canniff, Krystle Garth and Shaobong Li.

Using nucleic acids as a marker, researchers assessed how long measles and VZV viruses remained in the body after vaccination to identify the earliest time for transplantation to occur safely. They also compared the immune responses to the vaccines in children with CLD compared to healthy children.

Study participants included 21 children with CLD 6 to 13 months old and a control group of 13 healthy children 6 to 14 months old seen at the Child Health Clinic at Children’s Colorado. None had been vaccinated for MMR or VZV or had a history of infection.

Investigators found that measles virus RNA was undetectable by PCR in both groups within 14 days post-vaccination. While VZV DNA appeared by PCR in one CLD case at 21 days and one control at 28 days, VZV can be treated, if necessary, with anti-viral drugs. Investigators also found that vaccination triggered a protective immune response, either humoral or cell-mediated, in most children with CLD.

Clinical implications

This study, the first of its kind to assess postvaccination viral nucleic acid detection in children with CLD, demonstrated this population can clear measles virus RNA and VZV DNA in under four weeks. The data suggests that transplant can occur at 14 days post live viral vaccination instead of waiting a full four weeks.