The incidence rate and hospitalization rate of seasonal influenza in Beijing, 2018-2019

Abstract

Objective To estimate the incidence rate and hospitalization rate of seasonal influenza in Beijing, 2018-2019. Methods A multiplier model was used to estimate the incidence rate of influenza and hospitalization rate of influenza-associated severe acute respiratory infection (SARI) based on influenza surveillance data in Changping district and Huairou district of Beijing, including influenza-like illness (ILI) surveillance, pathogenic surveillance of influenza, SARI surveillance, as well as the data of health care service utilization. Results In 2018-2019 influenza season, the incidence rate of seasonal influenza was 5.4% (95%CI: 4.5%-7.4%) in Changping district and Huairou district. The influenza-associated SARI hospitalization rate was 31/100 000 (95%CI: 22/100 000-44/100 000). The ratio of hospitalization rate to incidence rate was about 1:174. The incidence was the highest among children aged 5-14 years old. Both hospitalization rate and the ratio of hospitalization rate to incidence rate were the highest among children aged < 5 years old. The incidence rate (2.3%, 95%CI: 1.9%-3.2%), influenza-associated SARI hospitalization rate (17/100 000, 95%CI: 11/100 000-28/100 000) and the ratio of hospitalization rate to incidence rate (1:137) related to influenza A (H1N1) pdm09 were higher than those related to any other subtype of influenza. Conclusions The disease burden of influenza was substantial among children. It is recommended to provide specific immunization program for children to prevent transmission of influenza. Key words: Influenza; Incidence; Hospitalization rate; multiplier model