Influenza-associated Hospitalization in Children Younger Than 5 Years of Age in Suzhou, China, 2011-2016

Pediatr Infect Dis J. 2019 May;38(5):445-452. doi: 10.1097/INF.0000000000002178.

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Child, Preschool
  • China / epidemiology
  • Cost of Illness
  • Epidemiological Monitoring
  • Female
  • Hospitalization / statistics & numerical data*
  • Hospitals, Pediatric
  • Humans
  • Infant
  • Infant, Newborn
  • Influenza, Human / epidemiology*
  • Influenza, Human / pathology*
  • Male
  • Prospective Studies
  • Risk Factors