The efficacy of alcohol-free hand sanitizers is heavily dependent on their ingredients and formulation . In the past, alcohol-free hand sanitisers tended to significantly under-perform alcohol or alcohol rubs as germ killers in clinical studies using standard protocols such as EN1500.
More recently, advanced formulations have been developed, some of which have been shown to out-perform alcohol. A further aspect of efficacy sometimes overlooked is the effect of repeated use.
The efficacy of alcohol as a hand disinfectant has been shown to decrease after repeated use, probably due to progressive adverse skin reactions, whereas the efficacy of an alcohol-free hand sanitiser based on Benzalkonium Chloride as its active active ingredient has been shown to increase with repeated use.
In a recent study, the effectiveness of alcohol was shown to decrease after repeated use. The study demonstrated that, unlike Benzalkonium Chloride, alcohol does not have persistent or cumulative antimicrobial activity after application.
Purell has been shown to fail to meet the FDA 21 CFR 333.470 performance standards for health-care personnel antiseptic hand washes not just as a consequence of the decrease in effectiveness with repeated use, but due to a lack of persistence in antimicrobial activity after application and the decrease in effectiveness with heavy soil loads.