influenza a/h3n2 and its co-infection with other respiratory pathogens: higher pneumonia rates and prolonged hospital stays in pediatric patients

Background: in pediatric populations, influenza viruses such as influenza b, influenza a/h1n1, and influenza a/h3n2 present unique clinical challenges due to their distinct characteristics. co-infections with other respiratory pathogens can lead to more severe disease progression in children, although the specific impacts of these co-infections are not yet fully understood. objectives: to explore the differences in clinical characteristics among children with single infections of influenza b, influenza a/h1n1, and influenza a/h3n2, and to assess the impact of co-infections with other respiratory pathogens on the severity of disease in children. methods: this retrospective study evaluated the severity of pediatric influenza hospitalizations during 2022 - 2023 by correlating virus types/subtypes with clinical outcomes, including pneumonia incidence, mechanical ventilation requirements, picu admissions, and duration of hospital stay. results: the study included 1,380 pediatric patients with influenza: 343 with influenza a/h1n1, 678 with a/h3n2, and 359 with influenza b. in children aged six and older, influenza a/h3n2 infection resulted in higher pneumonia rates and longer hospital stays compared to influenza a/h1n1 and influenza b (p < 0.05). laboratory result differences were also observed between single infections of influenza a and b in this age group. the co-infection rate for influenza a/h1n1 was 3.5%, significantly lower than that for h3n2 (11.9%) and influenza b (10.6%) (p < 0.05). clinical differences were noted between single and co-infections of influenza a/h3n2 and b, with co-infections showing higher pneumonia rates and longer hospital stays compared to single infections (p < 0.05). conclusions: in children aged six and older, influenza a/h3n2 is associated with higher rates of pneumonia and longer hospital stays. co-infections involving influenza b or a/h3n2 with additional respiratory pathogens further increase the risk of pneumonia and extend the duration of hospitalization.