RESEARCH ARTICLE


Correlation of ”Google Flu Trends“ with Sentinel Surveillance Data for Influenza in 2009 in Japan



Koji Wada*, Hiroshi Ohta, Yoshiharu Aizawa
Department of Public Health, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 252-0374, Japan.


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Creative Commons License
Wada et al.; Licensee Bentham Open

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Public Health, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 252-0374, Japan; Tel: +81-42-778-9352; Fax: +81-42-778-9257; E-mails: kwada-sgy@umin.ac.jp


Abstract

Google Flu Trends (http://www.google.org/flutrends/) (GFT) aggregates Google search data to estimate flu activity in 28 countries. This study explored the correlation of GFT with Japanese national sentinel surveillance data in 2009. We obtained GFT and national sentinel surveillance data for influenza in all 47 Japanese prefectures from 29 June- 31 Dec 2009. Pearson correlation coefficients were calculated between GFT and sentinel surveillance data in each prefecture. Multiple regression analysis was also used to determine associations between them. Correlation coefficients were greater than 0.9 between GFT and the sentinel surveillance data in Tokyo, Kanagawa, Aichi, Osaka, and Hyogo, which have relatively large populations. Peaks for GFT were 2 weeks earlier than sentinel surveillance in these prefectures. Multiple regressions showed that only Tokyo (r = 0.97; P < 0.01) was significantly associated with GFT. People's interest in influenza affects GFT data, which could reflect influenza spread in mega-cities such as Tokyo. Further development of technology to identify prefecture-wide epidemic patterns could offer more accurate information on influenza spread in Japan.

Keywords: Influenza, Google flu trend, sentinel surveillance, Japan.