Hospitalizations associated with influenza and respiratory syncytial virus among patients attending a network of private hospitals in South Africa, 2007-2012

Background: Influenza and respiratory syncytial virus (RSV) infection are common causes of lower respiratory tract illness. Data on their burden in low and middle-income settings and from Africa are scarce. We aimed to estimate age-specific rates of hospitalization attributable to influenza and RSV among patients attending private hospitals in South Africa during 2007 2012. Methods: We estimated annual age-specific rates of influenza- and RSV-associated hospitalization (that is respiratory hospitalizations likely due to influenza or RSV infection) by applying regression models to monthly administrative hospitalization data from a national private hospital group, using influenza and RSV surveillance data as covariates. Results: Estimated mean hospitalization rates associated with seasonal influenza were 75 (95% confidence interval (CI), 41 108) and 3 (95% CI, 2 5) per 100,000 person-years for all-respiratory and all-circulatory causes, respectively. Children <1 year and adults ≥75 years were the most affected, with influenza-associated all-respiratory hospitalization rates estimated at 255 (95% CI, 143 358) and 380 (95% CI, 227 506) per 100,000 person-years, respectively. Excess all-circulatory hospitalizations associated with seasonal influenza were only observed in adults ≥65 years. Annual hospitalization rates associated with RSV averaged an estimate of 223 (95% CI, 128 317) per 100,000 person-years for all-respiratory causes. Among children <1 year, RSV-associated all-respiratory hospitalization rate of 7,601 (95% CI, 4,312-10,817) per 100,000 person-years was estimated. Conclusions: Influenza and RSV substantially contributed to hospitalizations over the study period.