Influenza infection influencing factors and direct economic burden – A study based on hospitalized cases of severe acute respiratory infection (SARI)

Influenza viruses are one of the key pathogens causing acute respiratory infections in humans, which lead to significant economic burdens. From August 2023 to May 2024, hospitalized SARI cases were recruited from Shouguang People's Hospital in Weifang, Shandong Province. Reverse Transcription-Polymerase Chain Reaction was used to detect influenza virus nucleic acids, including influenza A and B viruses. Meanwhile, clinical information and detailed expense bills of these hospitalized SARI cases were collected to conduct analyses on demographics and clinical characteristics. In addition, cost analysis and investigation of factors influencing the economic burden of influenza were carried out from the perspectives of third-party payers and society. A total of 1,772 SARI cases were included in the study, with an influenza positivity rate of 7.5%. Among these cases, the proportion of hospitalized patients aged 70 y and above was the highest. Influenza viruses were more likely to result in severe illness or death, while influenza vaccination could significantly reduce the influenza positivity rate. The total medical insurance expenditure was $65,844.62, accounting for 64.3% of the total economic burden. For influenza-positive cases, the average direct medical burden was $783.95 per person, and the average out-of-pocket expenditure per patient was $288.88. Among the costs, laboratory testing fees and medication treatment fees accounted for the highest proportions. The study found that age, length of hospital stay, and vaccination status were factors influencing the direct medical economic burden of influenza. Influenza vaccination was significantly associated with the influenza positivity rate.