Influenza Complications in Children: The Experience of a Children’s Hospital in Romania and a Comparative Literature Review of Western and Eastern Studies

Background: Influenza infections have reached an approximate number of one billion cases annually in the general population. Hospitalization due to this infection is associated with high morbidity, and a proportion of hospitalized children may require ICU admission. In the United States of America, one in five children hospitalized due to influenza requires transfer to the intensive care unit (ICU). The real burden of this disease is not accurately known, especially for the pediatric population. Objective: The objective of this study was to define the characteristics of influenza-associated complications in pediatric patients hospitalized at a tertiary hospital in Brasov, Romania. Methods: This was an observational, retrospective study that gathered 258 influenza-infected patients aged from 0 up to 18 years old, hospitalized during the period from 1 January 2020 to 31 December 2025 at the Children’s Hospital of Brasov (a single-center study, but in a tertiary unit). The complications from this disease were categorized into respiratory, hematological, musculoskeletal, renal, ENT, cutaneous, rheumatological, and bacterial superinfections. Results: The patients were stratified according to their influenza type (A or B) and length of hospital stay. The length of stay was categorized as 0–4 days, 5–10 days, or >10 days. No significant association was observed between the influenza type and admission duration (χ2 = 2.185, df = 2, p = 0.3354). The most frequent complications were respiratory—bronchiolitis and pneumonia (22.8%)—followed by hematological (13.5%). Conclusions: The length of stay did not differ significantly between patients with influenza A and those with influenza B in the selected sample. The most common complications were respiratory, hematological, ENT, and neurological.