Evaluation of World Health Organization–Recommended Hand Hygiene Formulations

Miranda Suchomel; Maren Eggers; Steffen Maier; Axel Kramer; Stephanie J. Dancer; Didier Pittet

Disclosures

Emerging Infectious Diseases. 2020;26(9):2064-2068. 

In This Article

Abstract and Introduction

Abstract

As a result of the coronavirus disease pandemic, commercial hand hygiene products have become scarce and World Health Organization (WHO) alcohol-based hand rub formulations containing ethanol or isopropanol are being produced for hospitals worldwide. Neither WHO formulation meets European Norm 12791, the basis for approval as a surgical hand preparation, nor satisfies European Norm 1500, the basis for approval as a hygienic hand rub. We evaluated the efficacy of modified formulations with alcohol concentrations in mass instead of volume percentage and glycerol concentrations of 0.5% instead of 1.45%. Both modified formulations met standard requirements for a 3-minute surgical hand preparation, the usual duration of surgical hand treatment in most hospitals in Europe. Contrary to the originally proposed WHO hand rub formulations, both modified formulations are appropriate for surgical hand preparation after 3 minutes when alcohol concentrations of 80% wt/wt ethanol or 75% wt/wt isopropanol along with reduced glycerol concentration (0.5%) are used.

Introduction

Because commercial products are hardly or no longer available due to the coronavirus disease (COVID-19) pandemic, alcohol-based hand rub formulations for hygienic and surgical hand treatment published by the World Health Organization (WHO) in 2009[1] for local production in developing countries are now being produced for use in hospitals worldwide. As shown previously,[2] neither the formulation based on ethanol 80% vol/vol (WHO I) nor that based on isopropanol 75% vol/vol (WHO II), meets the efficacy requirements of the European Norm (EN) 12791,[3] which must be fulfilled to obtain approval as a surgical hand preparation in Europe. Each WHO-recommended formulation is also insufficient for hygienic hand antisepsis when 3 mL is applied for 30 seconds[4] according to the test method described in EN 1500.[5] The requirements can be met only if the volume is doubled (6 mL) and exposure is extended to 60 seconds.[4] But sufficient efficacy has been achieved by using modified WHO formulations with an increased alcohol concentration of 80% wt/wt ethanol or 75% wt/wt isopropanol at 3 mL for 30 seconds.[4]

On the basis of those results, we modified both WHO formulations by increasing their alcohol concentrations through changing their volume percentages into weight percentages and by prolonging the duration of application from 3 to 5 minutes. These modifications have been shown to render the immediate effects of both formulations noninferior to the reference of EN 12791, but this improvement was not observed for the so-called 3-hour effect (i.e., 3 hours after hand antisepsis).[6] Because the high glycerol concentration (1.45% vol/vol) of the original formulations has been shown to exert a negative influence on the 3-hour efficacy of alcohols,[7] we performed further studies by reducing the glycerol content of the WHO formulations by 50%. By increasing the alcohol concentration by ≈5% and reducing glycerol concentrations to 0.725%, both modified WHO formulations meet the efficacy requirements of EN 12791 when used for 5 minutes.[8] Although both new formulations were successfully tested for a 5-minute application, our suggestions for improving efficacy were not accepted by the WHO because the common duration for surgical hand preparation in most hospitals is 3 minutes. Furthermore, no information on dermal tolerability and healthcare workers' acceptance of these modified formulations was available.

In 2019, Menegueti et al[9] showed that a modified WHO I formulation containing only 0.5% glycerol led to better ratings of skin tolerance than the original WHO formulation containing 1.45% or a modification containing 0.75% glycerol. Because all such alternative formulations require testing for not only dermal tolerability but also for bactericidal performance, we investigated the efficacy of these modified WHO formulations (mass instead of volume percentage ethanol or isopropanol and 0.5% instead of 1.45% glycerol) according to EN 12791,[3] with an application duration of 3 minutes, as commonly used in surgical theaters in Europe.

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