Respiratory viral infections in patients with inherited metabolic disorders: Pathogen distribution and clinical outcomes.

Introduction: Children with inborn errors of metabolism (IEMs) are at increased risk for severe viral infections, which may precipitate acute metabolic decompensation, PICU admission, and death. Pathogen specific outcomes in this population remain poorly defined. The objective was to evaluate the epidemiology, viral etiology, and clinical severity of respiratory viral infections in hospitalized children with IEMs. Method: This single-center retrospective study included children with IMDs hospitalized with acute infectious illness and laboratory-confirmed respiratory viral detection during 2018-2024. Demographic features, underlying metabolic diagnoses, viral pathogens, and outcomes were evaluated. Result: A total of 45 infection episodes among 41 children were included; median age was 4 years (IQR:0.5-9.5), and 31 patients (75.6%) were male. The most common IEMs categories were amino acid metabolism disorders (36.6%) and complex molecule degradation and processing defects (26.8%). Respiratory disease was the predominant presentation (77.8%), followed by gastroenteritis (8.9%), sepsis (6.7%), and meningoencephalitis (6.7%). Acute metabolic decompensation occurred in 11/23 infection episodes in metabolically vulnerable patients (47.8%). Influenza was the most frequently identified virus (35.6%), followed by rhinovirus (22.2%), seasonal coronavirus (sCoV) (13.3%), and respiratory syncytial virus (11.1%). PICU admission was required in 13.3% (6/45) of cases. Infection-related mortality was 6.7% (n = 3), and all fatal cases had sCoV infection. Conclusion: Influenza was the most frequently identified pathogen, while sCoV was detected in all three infection-related deaths. Our results suggest that respiratory viral infections may be associated with clinical burden in children with IMDs, highlighting the importance of close clinical monitoring and supportive management in this vulnerable population.