During flu season, hand sanitizer is everywhere: in cubicles, classrooms and supermarkets.
But how effective is this "super" germ killer?
According to Centers for Disease Control and Prevention (CDC), the sanitizer doesn't work as well as washing for hands that are visibly dirty. It also doesn't eliminate all types of germs -- most notably, norovirus, a serious stomach bug that can spread quickly in schools.
The New York Times reports that influenza and many other common viruses are coated in envelope-like lipids that alcohol in sanitizer can rupture. But viruses that aren't coated, like norovirus, are often not affected by the sanitizer.
The NY Times cites a CDC study from 2011 that examined long-term care facilities and the outbreak of disease. The study found that at facilities where staff members used alcohol-based sanitizers, they were six times more likely to have an outbreak of norovirus than at locations where the staff preferred using soap and water.
The CDC says washing your hands with soap and water for at least 20 seconds is the most effective way to kill a wide variety of germs. If you're not so good at keeping track of time, officials suggest humming the "Happy Birthday" song from beginning to end -- twice -- to help you keep track.
But hand sanitizer can be an effective alternative if hand washing with soap and water isn't possible. Health officials say effective sanitizers should be at least 60 percent alcohol, but even these products don't work as well on hands that are visibly dirty.
While scientists and public health officials debate the effectiveness of hand sanitizers, what many don't debate is the prudence of erring on the safe side -- and not overestimating the power of these cleaners.
ABC News reports that in 2011, the U.S. Food and Drug Administration (FDA) charged four hand sanitizer and antispetic companies with claiming they could protect consumers against a possibly lethal form of a staph infection.
FDA accompanied this charge with a public press release that warned consumers of false claims on hand sanitizers.
"FDA has not approved any products claiming to prevent infection from MRSA, E. coli, Salmonella, or H1N1 flu, which a consumer can just walk into a store and buy” said Deborah Autor, compliance director at FDA’s Center for Drug Evaluation and Research. “These products give consumers a false sense of protection.”
Still, the hand sanitizer industry continues to be a profitable and growing one. According to a 2012 report from IBIS World, an independent publisher of U.S. industry research, sanitizer manufacturing is a $189.6 million industry and is growing by more than 5.5 percent every year.