New Findings Challenge the Efficiency of Hand Sanitizers During Flu Season

A newly published study in mSphere noted that rubbing hands with ethanol-based sanitizers have a lot of room for improvement to defend us against flu viruses.

The objective of the study was to examine the efficiency between the influenza A virus (IAV) and exposure to ethanol-based disinfectants (EBD) when in contact with infected patients.

Researchers at Kyoto Profectural University of Medicine first analyzed the physical properties of mucus, finding that ethanol spreads more slowly through the viscous substance than it does through saline.

Following this discovery, the researchers began the clinical portion of the study. They collected sputum, a mixture of saliva and mucus, from IAV-infected patients and dabbed them on participant’s fingers. After two minutes of exposure to EBD, the IAV virus remained active in the mucus of their fingertips. They found that fully deactivating the virus takes four minutes of exposure to EBD.

Due to the thick hydrogel structure of sputum, this prevents the ethanol from reaching and deactivating the IAV at a faster rate. Ryohei Hirose, Ph.D, MD., who led the study with Takaaki Nakaya, PhD, said that, "Until the mucus has completely dried, infectious IAV can remain on the hands and fingers, even after appropriate antiseptic hand rubbing."

Although previous studies have suggested that EBDs are effective against IAV, this study suggests that a splash of hand sanitizer, quickly applied, isn't enough. Hirose recommends that health care providers should be particularly cautious; if they don't adequately inactivate the virus between patients, they could enable its spread.

Both the CDC and World Health Organization recommend hand hygiene practices that include using EBDs for 15-30 seconds. However, according to the research team at Kyoto, the hand hygiene strategy that works the best against IAV infection is the traditional washing of hands- not just rubbing them. Washing hands with an antiseptic soap, they found, deactivated the virus within 30 seconds, regardless of whether the mucus remained wet or had dried.

Reference

Towards better hand hygiene for flu prevention.Science Dailywebsite. https://www.sciencedaily.com/releases/2019/09/190918131505.htm. Published September 18, 2019. Accessed September 19, 2019.