Dr. William Schaffner, infectious disease specialist, M.D., and professor of preventive medicine at the Vanderbilt University Medical Center, pointed out that liners may have more to do with providing comfort and reassurance to the user than actually doing anything to prevent disease.
Toilet seats were once thought to be a way of transmitting gastrointestinal or sexually transmitted infections, but that idea has since been refuted in research. Basically, the reason why those liners exist is because of toilets’ inherent “ick” factor, he says. That’s not to say that there aren’t disease-causing bacteria — such as E. coli and streptococcous — on a toilet seat. But as Dr. Philip Tierno, M.D., points out to Everyday Health, the skin on our behinds serves as an effective, protective barrier.
What does help to tamp down on the spread of gastrointestinal illness is hand-washing. After all, the CDC reports that using good old soap and water to wash your hands could lower diarrheal disease-related deaths as much as 50 percent (see recommendation from the WHO).