Correlation between National Influenza Surveillance Data and Search Queries from Mobile Devices and Desktops in South Korea

BackgroundDigital surveillance using internet search queries can improve both the sensitivity and timeliness of the detection of a health event, such as an influenza outbreak. While it has recently been estimated that the mobile search volume surpasses the desktop search volume and mobile search patterns differ from desktop search patterns, the previous digital surveillance systems did not distinguish mobile and desktop search queries. The purpose of this study was to compare the performance of mobile and desktop search queries in terms of digital influenza surveillance.Methods and ResultsThe study period was from September 6, 2010 through August 30, 2014, which consisted of four epidemiological years. Influenza-like illness (ILI) and virologic surveillance data from the Korea Centers for Disease Control and Prevention were used. A total of 210 combined queries from our previous survey work were used for this study. Mobile and desktop weekly search data were extracted from Naver, which is the largest search engine in Korea. Spearman’s correlation analysis was used to examine the correlation of the mobile and desktop data with ILI and virologic data in Korea. We also performed lag correlation analysis. We observed that the influenza surveillance performance of mobile search queries matched or exceeded that of desktop search queries over time. The mean correlation coefficients of mobile search queries and the number of queries with an r-value of ≥ 0.7 equaled or became greater than those of desktop searches over the four epidemiological years. A lag correlation analysis of up to two weeks showed similar trends.ConclusionOur study shows that mobile search queries for influenza surveillance have equaled or even become greater than desktop search queries over time. In the future development of influenza surveillance using search queries, the recognition of changing trend of mobile search data could be necessary.背景：利用互联网搜索查询开展的数字监测，可提升流感暴发等健康事件检测的灵敏度与时效性。尽管近期有研究指出，移动搜索量已超越桌面端搜索量，且二者的搜索模式存在显著差异，但既往数字监测系统并未对移动与桌面端搜索查询加以区分。本研究旨在对比移动与桌面端搜索查询在流感数字监测中的应用性能。 方法与结果：本研究的时间范围为2010年9月6日至2014年8月30日，涵盖4个流行病学年度。研究使用了韩国疾病控制与预防中心提供的流感样病例（Influenza-like illness, ILI）及病毒学监测数据，共采用前期调研中整理的210组组合搜索查询词。移动与桌面端的周度搜索数据均提取自韩国最大搜索引擎Naver。本研究采用斯皮尔曼相关分析，探究韩国地区移动、桌面端搜索数据与流感样病例及病毒学监测数据之间的相关性，并开展了滞后相关分析。结果显示，随着时间推移，基于移动搜索查询的流感监测性能可媲美甚至超越桌面端搜索查询；在4个流行病学年度内，移动搜索查询的平均相关系数，以及r值≥0.7的查询词占比，均达到或超过桌面端搜索的对应水平。最长滞后两周的滞后相关分析也呈现出相似趋势。 结论：本研究表明，用于流感监测的移动搜索查询的监测性能已可媲美甚至超越桌面端搜索查询。未来在基于搜索查询的流感监测系统开发中，需重视移动搜索数据的变化趋势。