According to computer scientist Mark Drezde, “Our goal was to find out whether Twitter posts could be a useful source of public health information and we determined that indeed they could. In some cases, we probably learned things that even the tweeters’ doctors were not aware of, such as which over-the-counter medicines the posters were using to treat their symptoms at home.”
So far, researchers actually fed 2 billion public tweets that were posted between May 2009 and October 2010 into computers, and a special kind of software was used to filter those messages. The result? A cool 1.5 million messages that actually referred to health matters, which is less than 1%, but still useful enough to draw certain conclusions. Just bear in mind that whatever data collected cannot be taken as the whole, since a huge portion of the world does not use Twitter at the moment, especially those living in underdeveloped countries and do not have access to proper communications infrastructure.