Incidence and severity of SARS-CoV-2 infection and vaccine BNT162 side effects in children and adolescents with Noonan Syndrome: a national multicentric study.

Background: Pre-existing medical conditions are known to increase the risk of severe coronavirus disease 2019 (COVID-19), even in pediatric populations. This study aimed to evaluate the symptoms and severity of COVID-19, as well as the side effects of the BNT162 vaccine, in children and adolescents with Noonan Syndrome (NS) compared to healthy controls. Methods: A retrospective and prospective multicenter study was conducted across Italy. Clinical characteristics, course, and duration of SARS-CoV-2 infection, as well as side effects of the BNT162 vaccine, were compared between 97 patients with NS and 97 age- and sex-matched healthy subjects. Results: No statistically significant differences were found in the severity or duration of COVID-19 between NS patients and controls. NS patients exhibited a higher rate of rhinorrhea during SARS-CoV-2 infection (69.2% vs. 46%, p < 0.05), whereas anosmia was more common among controls (1.5% vs. 12.7%, p < 0.05). No statistically significant differences in side effects from the BNT162 vaccine were observed between groups. 95% confidence intervals were calculated for key outcomes to improve comparability. Conclusion: Children and adolescents with Noonan Syndrome generally experience a mild course of COVID-19 and show no evidence of increased vaccine-related risk. Despite the small sample size and the rarity of severe events, these findings yield valuable insights for patients living with this rare disease.