Between December 2012 and January 2013, using a sample of 20 popular health-related websites, Huesch used freely available privacy tools to detect third parties. Commercial interception software also was used to intercept hidden traffic from the researcher's computer to the websites of third parties.

Huesch found that all 20 sites had at least one third-party element, with the average being six or seven. Thirteen of the 20 websites had one or more tracking element. No tracking elements were found on physician-oriented sites closely tied to professional groups. Five of the 13 sites that had tracker elements had also enabled social media button tracking. Using the interception tool, searches were leaked to third-party tracking entities by seven websites. Search terms were not leaked to third-party tracking sites when done on U.S. government sites or four of the five physician-oriented sites, according to the study results.

"Failure to address these concerns may diminish trust in health-related websites and reduce the willingness of some people to access health-related information online," the study concludes.