Studying the burden and risk factors associated with severe illness from influenza infection in young children in eastern China will contribute to future cost-effectiveness analyses of local influenza vaccine programs.
We conducted prospective, severe acute respiratory infection (SARI) surveillance at Suzhou University–Affiliated Children’s Hospital to estimate influenza-associated hospitalizations in Suzhou University–Affiliated Children’s Hospital by month in children younger than 5 years of age from October 2011 to September 2016. SARI was defined as fever (measured axillary temperature ≥ 38°C) and cough or sore throat or inflamed/red pharynx in the 7 days preceding hospitalization. We combined SARI surveillance data with healthcare utilization survey data to estimate and characterize the burden of influenza-associated SARI hospitalizations in Suzhou within this age group in the 5-year period.
Of the 36,313 SARI cases identified, 2,297 from respiratory wards were systematically sampled; of these, 259 (11%) were influenza positive. Estimated annual influenza-associated SARI hospitalization rates per 1,000 children younger than 5 years of age ranged from 4 (95% confidence interval [CI], 2–5) in the 2012–2013 season to 16 (95% CI, 14–19) in the 2011–2012 season. The predominant viruses were A/H3N2 (59%) in 2011–12, both A/H1N1pdm09 (42%) and B (46%) in 2012–13, A/H3N2 (71%) in 2013–14, A/H3N2 (55%) in 2014–15 and both A/H1N1pdm09 (50%) and B (50%) in 2015–16. The age-specific influenza-associated SARI hospitalization rates for the 5-year period were 11 (95% CI, 8–15) per 1,000 children 0–5 months of age; 8 (95% CI, 7–10) per 1,000 children 6–23 months of age and 5 (95% CI, 4–5) per 1,000 children 24–59 months of age, respectively.
From 2011 to 2016, influenza-associated SARI hospitalization rates in children aged younger than 5 years of age in Suzhou, China, were high, particularly among children 0–5 months of age. Higher hospitalization rates were observed in years where the predominant circulating virus was influenza A/H3N2. Immunization for children > 6 months, and maternal and caregiver immunization for those < 6 months, could reduce influenza-associated hospitalizations in young children in Suzhou.
From the *Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China
†Suzhou University Affiliated Children’s Hospital, Suzhou, China
‡Suzhou Center for Disease Prevention and Control, Suzhou, China
§Centers for Disease Control and Prevention, Atlanta, GA.
Accepted for publication July 30, 2018.
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
This study was supported by the China-U.S. Collaborative Program on Emerging and Re-Emerging Infectious Diseases (5U2GGH000018), the Shanghai Municipal Health and Family Planning (15GWZK0101 and GWTD2015S05).
The authors have no conflicts of interest to disclose.
Drs. Yu and Zhang contributed equally to this work.
Address for correspondence: Genming Zhao, PhD, Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Address:130 Dong'an Road, Xuhui District, Shanghai, P.R.China, 200032. E-mail: firstname.lastname@example.org or Tao Zhang, PhD, Department of Epidemiology, School of Public Health, Fudan University, Address:130 Dong'an Road, Xuhui District, Shanghai, P.R.China, 200032. E-mail: email@example.com.