Most governments agree on the public health advice that soap and water is most effective for hand washing - but to use hand sanitizer where soap and water may not be available.
The original advice to consumers was to use an alcohol-based hand sanitizer that contained at least 60% alcohol. This was the advice from the FDA and Centers for Disease Control and Prevention (CDC) and the Therapeutic Goods Administration (TGA) in Australia.
However, the advice has now changed to reflect the recommendation of the World Health Organization (WHO) for hand sanitizer formulas to contain 80% ethanol or 75% isopropyl alcohol, as well as inclusion of 0.125% hydrogen peroxide.
We decided to do our own desktop investigations into published scientific research on the efficacy of alcohol and were surprised with what we found. In fact as an antibacterial, 60% alcohol doesn’t cut it unless you are willing to undergo a 5+ minute exposure time , as published by Dr Andreas Sauerbrei of the Institute of Medical Microbiology, Jena University Hospital, Jena, Germany. Interestingly when these data are used to assess alcohol’s antiviral properties, efficacy starts to occur at 60% for some viruses, but full potency is achieved at 80+% concentration.
Sauerbrei's published results in MicrobiologyOpen suggest that a safe bactericidal effect of ethanol can be expected at between concentrations and exposure times of 60% @ ≥ 5.0 minutes, and 85% @ ≤ 0.5 minutes, respectively.
Interestingly, their data demonstrates a loss of anti-bacterial efficacy at even higher concentrations. Conversely for alcohol's anti-viral efficacy, they reported that ethanol exerts low level virucidal activity against enveloped viruses (plus adeno-, noro-, and rotaviruses) at an exposure time of up to 5 minutes, at a minimum 80%-90% concentration.