"Influenza "rate is slightly lowered in a population with [China's] one-child policy" ("consequences include decreased fertility rates, population aging, decreased household sizes, changes in family structure, and imbalanced sex ratios."

PLoS One. 2014 Feb 6;9(2):e84961. doi: 10.1371/journal.pone.0084961. eCollection 2014.

Effect of the one-child policy on influenza transmission in china: a stochastic transmission model.

Liu F1, Enanoria WT2, Ray KJ3, Coffee MP1, Gordon A4, Aragón TJ5, Yu G6, Cowling BJ7, Porco TC8.

Author information

• 1F.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.
• 2F.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.
• 3F.I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America.
• 4Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America.
• 5Center 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.
• 6West of China Institute of Environmental Health, Northwest University for Nationalities, Lanzhou, Gansu, China.
• 7School of Public Health, The University of Hong Kong, Hong Kong, China.
• 8F.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.

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?

METHODS AND FINDINGS:

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-childpolicy 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.