John’s Hopkins University does. That is according to Charles Corley, a grad student at Boston University:

“It may seem that the information posted on Twitter isn’t all that useful. Who cares if people tweet about waking up with a case of the sniffles? Johns Hopkins University, for one. Researchers Mark Dredze and Michael Paul analyzed 2 billion tweets posted between May 2009 and October 2010 to track health trends. These tweets were run through a computer and whittled down to 1.5 million posts relating to various health care issues ranging from the ailments people suffered to the sort of medication they were using. Based on the data, they were able to track the rate of infection for viruses such as the flu during this time period. Surprisingly, the influenza rate implied by tweets nearly matched the Centers for Disease Control and Prevention’s own findings during that time. So seemingly inane tweets about runny noses can allow the health care industry to prepare for disease outbreaks.”