SARS-COV2 vaccine effiacy in pediatric kidney transplant recipients

This study aimed to evaluate the humoral and cellular immune responses following Pfizer-BioNTech (BNT162b2) mRNA COVID-19 vaccination in 36 pediatric and adolescent patients diagnosed with chronic kidney disease (CKD) who had either undergone kidney transplantation or were receiving hemodialysis. The mean age of the study population was 17.5 years, with 24 (66.7%) male and 12 (33.3%) female participants. Among them, 31 patients (86.1%) were kidney transplant recipients, while 5 patients (13.9%) were on maintenance hemodialysis due to CKD. Following mRNA vaccination, the seropositivity rate was 78.9% at the 1st month and reached 100% at the 12th-month assessment. The mean antibody titers were 84.96 RU/mL at 1 month and 107.18 RU/mL at 12 months. Patients who received three or more doses of mRNA vaccine exhibited significantly higher antibody levels at both the 1st month (mean: 106.3 RU/mL; p = 0.012) and 12th month (mean: 118.5 RU/mL; p = 0.038) compared to those who received two or fewer doses. Additionally, a positive correlation was observed between age and antibody titers (r = 0.403; p = 0.041), suggesting that older age may be associated with a stronger humoral immune response. Cellular immunity, assessed using the IGRA test, was positive in 92.3% of tested patients; however, results were invalid in 13 patients due to technical limitations. No serious adverse events or clinically significant side effects related to vaccination were observed in any patient. During the follow-up period, all COVID- 19 infections among vaccinated individuals were mild, and no cases required hospitalization or resulted in severe disease or complications. These findings demonstrate that mRNA-based COVID-19 vaccines induce robust and durable humoral and cellular immune responses in pediatric kidney transplant and CKD patients while maintaining a favorable safety and tolerability profile. The results support the implementation of individualized and multi-dose vaccination strategies in high-risk pediatric populations under immunosuppressive therapy to ensure long-term immunological protection and clinical efficacy. Keywords: Pediatric kidney transplantation, COVID-19, mRNA vaccine, humoral immunity, cellular immunity