Background: Studies in adults have demonstrated a risk for allograft rejection or development of donor-specific antibodies (DSA) following SARS-CoV-2 vaccination.  We examined the incidence of acute rejection and de novo DSA following COVID-19 vaccination or infection among pediatric kidney transplant patients.
Methods: Retrospective analysis of 23 pediatric kidney transplant recipients without prior history of rejection and DSA who received SARS-CoV-2 mRNA vaccine. Risk for rejection was evaluated via monitoring of serum creatinine, DSA, and donor-derived cell-free DNA per center protocol. Results concerning for rejection prompted allograft biopsy, graded by the Banff classification system.
Results: 8 of 23 (34.8%) received 2-doses of SARS-CoV-2 mRNA vaccine, 15 (65.3%) received 3 doses. Two (8.7%) had rejection; one with de novo DSA, another without. There was no difference in the number of doses of COVID-19 vaccine received in those with rejection vs. no rejection (p=0.53). 13 (56.5%) developed SARS-CoV-2 infection, with no difference in the number of vaccines received between those infected with COVID-19 vs. those who were not (p = 0.69). No adjustments were made to maintenance immunosuppression during SARS-CoV-2 infection and there was no rejection or DSA formation after infection (Table 1). Median follow-up time was 29.9 months (IQR 25.0-33.4 months) after the first vaccine dose.

Conclusion: In our small single center cohort, SARS-CoV-2 vaccination or infection did not appear to increase the risk for rejection or de novo DSA in pediatric kidney transplant recipients. Larger prospective studies are needed to further understand the immune effects of COVID-19 vaccine and disease in this population.