Using Google Trends for influenza surveillance in South China

PLoS One. 2013;8(1):e55205. doi: 10.1371/journal.pone.0055205. Epub 2013 Jan 25.


Background: Google Flu Trends was developed to estimate influenza activity in many countries; however there is currently no Google Flu Trends or other Internet search data used for influenza surveillance in China.

Methods and findings: Influenza surveillance data from 2008 through 2011 were obtained from provincial CDC influenza-like illness and virological surveillance systems of Guangdong, a province in south China. Internet search data were downloaded from the website of Google Trends. Pearson's correlation coefficients with 95% confidence intervals (95% CI) were calculated to compare surveillance data and internet search trends. The correlation between CDC ILI surveillance and CDC virus surveillance was 0.56 (95% CI: 0.43, 0.66). The strongest correlation was between the Google Trends term of Fever and ILI surveillance with a correlation coefficient of 0.73 (95% CI: 0.66, 0.79). When compared with influenza virological surveillance, the Google Trends term of Influenza A had the strongest correlation with a correlation coefficient of 0.64 (95% CI: 0.43, 0.79) in the 2009 H1N1 influenza pandemic period.

Conclusions: This study shows that Google Trends in Chinese can be used as a complementary source of data for influenza surveillance in south China. More research in the future should develop new models using search trends in Chinese language to estimate local disease activity and detect early signals of outbreaks.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • China / epidemiology
  • Disease Outbreaks
  • Humans
  • Influenza, Human / epidemiology*
  • Internet*
  • Population Surveillance / methods*
  • Software*

Grant support

This study was supported by the key medical specialty program-Field Epidemiology and Medical Scientific Research Foundation of Guangdong Province Grant A2010067 (Research on patterns of transmission and intensity of epidemic of Pandemic Influenza H1N1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.