[Estimating the disease burden of seasonal influenza in China, 2006-2019]

Objective: To estimate the health impact and economic burden of seasonal influenza in mainland China. Methods: From systematic literature reviews, we collected the influenza-associated excess influenza-like-illness (ILI) outpatient consultation rates, hospitalization rates of severe acute respiratory infections (SARI) and respiratory excess mortality, 2006-2017. Using these data, as well as demographic data (2019), the number of influenza-associated excess ILI outpatient consultations, SARI hospitalizations and respiratory excess deaths were estimated. Then using per capita economic burden of influenza-associated outpatient consultations and hospitalizations, as well as the productivity loss of influenza-related premature deaths, the annual influenza-associated total economic burden was estimated. All costs were adjusted to 2019 using the consumer price index. Results: The annual influenza-associated excess ILI outpatient consultations, SARI hospitalizations and excess respiratory deaths were 3 million, 2.34 million, 0.09 million, respectively. The total economic burden was 26.38 billion CNY, accounting for 0.266‰ GDP in 2019, of which the hospitalization-related economic burden accounted for the highest proportion (86.4%, 22.79 billion CNY), followed by the outpatient-related economic burden (11.3%, 2.97 billion CNY), and the indirect economic burden of productivity loss of premature deaths was the lowest (2.4%, 0.62 billion CNY). Largest economic burden was observed in East China (10.51 billion CNY) and smallest observed in Northeast China (0.38 billion CNY). Conclusion: The health burden of influenza-related outpatient visits and hospitalizations were substantial. The economic burden of influenza-related SARI hospitalization was higher than that of influenza-related outpatients and pre-mature deaths. The highest economic burden of influenza occurred in the East China.