Assessing clinical benefits of live-attenuated vaccination in post-liver transplant patients: Analysis of breakthrough infections and natural boosters

Recently, live-attenuated measles, rubella, varicella, and mumps vaccines have been administered to carefully selected post-liver transplant patients. Although attention has been focused on post-vaccination antibody titers and adverse events, the real-life clinical benefits remain unclear. A comprehensive analysis of breakthrough infections and natural boosters (asymptomatic cases with significant elevation in virus antibody titers) following immunization post-liver transplantation was conducted from 2002-2023, exploring the timing, frequency, correlation with domestic outbreaks, and degree of antibody elevation. During the median 10-year observation period among 68 post-liver transplant patients, breakthrough infections occurred only in chickenpox, with 7 mild cases (1 episode/64 person-years). A total of 59 natural booster episodes (1, 5, 20, and 33 for measles, rubella, chickenpox, and mumps, respectively) were observed, with incidence rates of 1 per 569, 110, 22, and 17 person-years, respectively. The timing of natural boosters closely correlated with domestic outbreaks (P < .05 in chickenpox and mumps), influenced by local vaccine coverage. The degree of antibody elevation was significantly higher in individuals with breakthrough infections than in those with natural boosters (P < .05). These findings suggest that immunization with live-attenuated vaccines for post-liver transplant patients has demonstrated clinical benefits. Furthermore, mass vaccination has a positive impact on post-transplant patient outcomes.