Quick use of hand sanitizers may not be enough to kill flu virus: study

Kyoto, Japan — Researchers want health care professionals to understand the limits of hand sanitizers, after their study showed that ethanol-based sanitizers can take up to four minutes to disinfect hands that carry the flu virus.

Researchers from the Kyoto Prefectural University of Medicine placed wet and dry mucus from patients infected with the influenza A virus onto the hands of 10 volunteers and then applied hand sanitizer.

The virus in the wet mucus took four minutes to become inactivated by the hand sanitizer. When the mucus was allowed to fully dry, which took 30 minutes, the hand sanitizer needed only 30 seconds to deactivate the virus. Further, the use of soap and water inactivated the virus in the infected mucus – both wet and dry – within 30 seconds.

According to the researchers, the thick viscosity of mucus seems to protect the virus from the impact of hand sanitizers. When mucus is wet, the active virus can remain on the hands when the sanitizer is on the hands for less than four minutes. The researchers encourage the use of handwashing to deactivate the virus.

The Centers for Disease Control and Prevention recommends washing hands with soap and water, but if these are not available, an alcohol-based hand sanitizer that contains at least 60% alcohol is suggested. The agency recommends rubbing hand sanitizer on all surfaces of your hands and fingers until dry, which should take about 20 seconds.

The Kyoto researchers, however, note that 80% ethanol-based hand sanitizers are most effective.

The study was published online Sept. 18 in mSphere, the journal of the American Society for Microbiology.