Although tracking software such as cookies is a common feature on websites, the NHS is the only prestigious site-one that is linked to government or a professional association-that is leaking the data to third parties.
It's not known if the NHS receives money for leaking the data, says Marco Huesch, a researcher at the University of Southern California. Huesch tracked 20 popular health sites, and discovered that six used third-party tracking software. These included Medline Plus, PubMed, the Centers for Disease Control (CDC), National Cancer Institute, WebMD and the NHS. But, of these, only the NHS was leaking the data to third parties. Others that were tracking and leaking the data included the New York Times and Men's Health sites.
Data being leaked included search terms and the way people navigate around the site. Although site visits may be anonymous, and people do not have to leave their name or email address, they can still be identified by their computer's IP address. Huesch says his discovery could damage the trust people have in 'official' health websites. The NHS is the UK's most popular health web site.
(Source: JAMA Internal Medicine, 2013; doi: 10.1001/jamainternmed.2013.7795).