title: Correlation between national influenza surveillance data and google trends in South Korea.
abstract: BACKGROUND
  In South Korea, there is currently no syndromic surveillance system using internet search data, including Google Flu Trends. The purpose of this study was to investigate the correlation between national influenza surveillance data and Google Trends in South Korea.
  
  
  METHODS
  Our study was based on a publicly available search engine database, Google Trends, using 12 influenza-related queries, from September 9, 2007 to September 8, 2012. National surveillance data were obtained from the Korea Centers for Disease Control and Prevention (KCDC) influenza-like illness (ILI) and virologic surveillance system. Pearson's correlation coefficients were calculated to compare the national surveillance and the Google Trends data for the overall period and for 5 influenza seasons.
  
  
  RESULTS
  The correlation coefficient between the KCDC ILI and virologic surveillance data was 0.72 (p<0.05). The highest correlation was between the Google Trends query of H1N1 and the ILI data, with a correlation coefficient of 0.53 (p<0.05), for the overall study period. When compared with the KCDC virologic data, the Google Trends query of bird flu had the highest correlation with a correlation coefficient of 0.93 (p<0.05) in the 2010-11 season. The following queries showed a statistically significant correlation coefficient compared with ILI data for three consecutive seasons: Tamiflu (r = 0.59, 0.86, 0.90, p<0.05), new flu (r = 0.64, 0.43, 0.70, p<0.05) and flu (r = 0.68, 0.43, 0.77, p<0.05).
  
  
  CONCLUSIONS
  In our study, we found that the Google Trends for certain queries using the survey on influenza correlated with national surveillance data in South Korea. The results of this study showed that Google Trends in the Korean language can be used as complementary data for influenza surveillance but was insufficient for the use of predictive models, such as Google Flu Trends.
authors: Department of Emergency Medicine, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, South Korea.
authors: Sungjin
authors: S
authors: Cho
authors: Chang Hwan
authors: CH
authors: Sohn
authors: Min Woo
authors: MW
authors: Jo
authors: Soo-Yong
authors: SY
authors: Shin
authors: Jae Ho
authors: JH
authors: Lee
authors: Seoung Mok
authors: SM
authors: Ryoo
authors: Won Young
authors: WY
authors: Kim
authors: Dong-Woo
authors: DW
authors: Seo
mesh_terms: D016208:Databases, Factual; D062665:Epidemiological Monitoring; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology*; D056910:Republic of Korea / Q000453:epidemiology; D057386:Search Engine; D013997:Time Factors