Epidemiological, clinical characteristics and the association between influenza vaccination, oseltamivir treatment, and complications in children with seasonal influenza

Influenza, a historical and contemporary public health challenge, is an acute respiratory infection caused mainly by influenza A or B viruses. This descriptive case series describes 194 children treated for seasonal influenza at the Department of Pediatrics, 103 Military Hospital, Vietnam Military Medical University, from May 2022 to May 2023. Influenza primarily occurred during winter and early spring, peaking in December and January, 57.2% were aged 12-60 months, boys. Vaccination coverage was limited (36.3%), especially post-COVID-19. Complications were seen in 75.3% of the cases, including febrile seizures (42.3%), bronchopneumonia (40.2%), respiratory failure (8.2%), acute myocarditis, influenza-associated encephalopathy, and septic shock. The study reveals bacterial coinfections, affected 20% of the cases, mainly by Streptococcus pneumoniae and S. aureus, and atypical bacteria Mycoplasma pneumoniae. Non-vaccinated children faced significantly higher risks of complications, oseltamivir within 48 hours reducing the risks of complications. Influenza predominantly affects 12-60 month-olds, males, and peaks annually in winter. Severe conditions stem from bacterial coinfections, emphasizing the importance of vaccination and prompt antiviral treatment to mitigate complications. The study highlights a critical need for increased vaccination, especially in the post-COVID-19 era, to manage influenza in children effectively.