title: Effect of the one-child policy on influenza transmission in China: a stochastic transmission model.
abstract: BACKGROUND
  China's one-child-per-couple policy, introduced in 1979, led to profound demographic changes for nearly a quarter of the world's population. Several decades later, the consequences include decreased fertility rates, population aging, decreased household sizes, changes in family structure, and imbalanced sex ratios. The epidemiology of communicable diseases may have been affected by these changes since the transmission dynamics of infectious diseases depend on demographic characteristics of the population. Of particular interest is influenza because China and Southeast Asia lie at the center of a global transmission network of influenza. Moreover, changes in household structure may affect influenza transmission. Is it possible that the pronounced demographic changes that have occurred in China have affected influenza transmission?
  
  
  RESULTS
  To address this question, we developed a continuous-time, stochastic, individual-based simulation model for influenza transmission. With this model, we simulated 30 years of influenza transmission and compared influenza transmission rates in populations with and without the one-child policy control. We found that the average annual attack rate is reduced by 6.08% (SD 2.21%) in the presence of the one-child policy compared to a population in which no demographic changes occurred. There was no discernible difference in the secondary attack rate, -0.15% (SD 1.85%), between the populations with and without a one-child policy. We also forecasted influenza transmission over a ten-year time period in a population with a two-child policy under a hypothesis that a two-child-per-couple policy will be carried out in 2015, and found a negligible difference in the average annual attack rate compared to the population with the one-child policy.
  
  
  CONCLUSIONS
  This study found that the average annual attack rate is slightly lowered in a population with a one-child policy, which may have resulted from a decrease in household size and the proportion of children in the population.
authors: F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America ; Center for Infectious Diseases and Emergency Readiness, School of Public Health, University of California, Berkeley, California, United States of America.
authors: Fengchen
authors: F
authors: Liu
authors: F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America ; Center for Infectious Diseases and Emergency Readiness, School of Public Health, University of California, Berkeley, California, United States of America ; Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America.
authors: Wayne T A
authors: WT
authors: Enanoria
authors: F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America.
authors: Kathryn J
authors: KJ
authors: Ray
authors: F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America ; Center for Infectious Diseases and Emergency Readiness, School of Public Health, University of California, Berkeley, California, United States of America.
authors: Megan P
authors: MP
authors: Coffee
authors: Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America.
authors: Aubree
authors: A
authors: Gordon
authors: Center for Infectious Diseases and Emergency Readiness, School of Public Health, University of California, Berkeley, California, United States of America ; Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America.
authors: Tomás J
authors: TJ
authors: Aragón
authors: West of China Institute of Environmental Health, Northwest University for Nationalities, Lanzhou, Gansu, China.
authors: Guowei
authors: G
authors: Yu
authors: School of Public Health, The University of Hong Kong, Hong Kong, China.
authors: Benjamin J
authors: BJ
authors: Cowling
authors: F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America ; Center for Infectious Diseases and Emergency Readiness, School of Public Health, University of California, Berkeley, California, United States of America ; Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, California, United States of America.
authors: Travis C
authors: TC
authors: Porco
mesh_terms: D000293:Adolescent; D002648:Child; D002681:China / Q000453:epidemiology; D003198:Computer Simulation; D003710:Demography; D016656:Family Planning Policy; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000635:transmission*; D008297:Male; D008954:Models, Biological; D013269:Stochastic Processes