Pediatric Liver and Kidney Transplant Recipients Demonstrate Greater Serological Response to SARS-CoV-2 Vaccination Than Adults

Background. Adult solid organ transplant recipients (SOTRs) have decreased responsiveness to severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) vaccination and higher incidence of infection, but there are few data on the serological response in pediatric SOTR. The aim of this study was to determine serological response to SARS-CoV-2 vaccination in pediatric liver (LT) and kidney transplant (KT) recipients and compare it with adult SOTR. Methods. A European, prospective, multicenter study was performed. Samples were taken at 7 and 32 wk following COVID-19 vaccination and serological endpoints were measured by ELISA. Results. A total of 42 pediatric (16 post-LT and 26 post-KT) and 117 adult (all post-LT) were included. All pediatric participants and 94% adult participants received mRNA vaccines. Paediatric SOTR patients had significantly higher anti-Spike IgG levels than adult participants at week 7 (114 220.7 [59 285.92-220 058.55] versus 8756.7 [5643.69-13 586.71], P < 0.0001) and week 32 (46 113.2 [10 992.91-193 436.14] versus 8207.0 [3561.20-18 913.43], P = 0.0032). No significant difference in week 7 anti-Spike IgG response was found between pediatric LT and KT (129 434.4 [51 888.64-322 869.69] versus 105 304.5 [39 910.20-277 849.50], P = 0.9854). No differences were seen between children and adults in the rate of decline of anti-Spike IgG between weeks 7 and 32 (P = 0.8000). Male sex and hemolytic-uremic syndrome or postischemic kidney disease were associated with lower anti-Spike IgG levels at week 7 in pediatric SOTR. Conclusions. Paediatric SOTR demonstrate greater SARS-CoV-2 vaccine responses than comparable adult SOTR patients. These data support efficacy and safety of SARS-CoV-2 vaccination in child SOTR and may alleviate vaccine hesitancy in this patient group.