Costs of Influenza Illness and Acute Respiratory Infections by Household Income Level: Catastrophic Health Expenditures and Implications for Health Equity.

Background: Seasonal influenza illness and acute respiratory infections can impose a substantial economic burden in low- and middle-income countries (LMICs). We assessed the cost of influenza illness and acute respiratory infections across household income strata.
Methods: We conducted a secondary analysis of data from a prior systematic review of costs of influenza and other respiratory illnesses in LMICs and contacted authors to obtain data on cost of illness (COI) for laboratory-confirmed influenza-like illness and acute respiratory infection. We calculated the COI by household income strata and calculated the out-of-pocket (OOP) cost as a proportion of household income.
Results: We included 11 studies representing 11 LMICs. OOP expenses, as a proportion of annual household income, were highest among the lowest income quintile in 10 of 11 studies: in 4/4 studies among the general population, in 6/7 studies among children, 2/2 studies among older adults, and in the sole study for adults with chronic medical conditions. COI was generally higher for hospitalizations compared with outpatient illnesses; median OOP costs for hospitalizations exceeded 10% of annual household income among the general population and children in Kenya, as well as for older adults and adults with chronic medical conditions in China.
Conclusions: The findings indicate that influenza and acute respiratory infections pose a considerable economic burden, particularly from hospitalizations, on the lowest income households in LMICs. Future evaluations could investigate specific drivers of COI in low-income household and identify interventions that may address these, including exploring household coping mechanisms. Cost-effectiveness analyses could incorporate health inequity analyses, in pursuit of health equity.
(© 2025 The Author(s). Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)