Wikipedia
The term "infodemiology" (and the closely related term infoveillance) has been coined by Canadian researcher Gunther Eysenbach. Eysenbach defines "infodemiology" (or information epidemiology) as a "new research discipline and methodology [which deals with] the study of the determinants and distribution of health information [on the Internet]", with the ultimate goal to improve public health
Eysenbach first used the term in the context of measuring and predicting the quality of health information on the web (i.e., measuring the "supply" side of information). He later included into his definition methods and techniques which are designed to automatically measure and track health information "demand" (e.g., by analyzing search queries) as well as "supply" (e.g., by analyzing postings on webpages, in blogs, and news articles, for example through GPHIN) on the Internet with the overarching goal to inform public health policy and practice. In 2013, the Infovigil Project was launched in an effort bring the research community together to help realize this goal, and is funded by the Canadian Institutes of Health Research.
In a seminal paper Eysenbach demonstrated his point by showing a correlation between flu-related searches on Google (demand data) and flu- incidence data. The method is shown to be better and more timely (i.e., can predict public health events earlier) than traditional syndromic surveillance methods such as reports by sentinel physicians.