Background: The World Health Organization (WHO) has published "Guidelines on Hand Hygiene in Health Care" recommending 2 hand rub formulations based on 80% vol/vol ethanol or 75% vol/vol isopropanol for local production in healthcare settings where commercial products are not available or are too expensive. Previous investigations have shown that neither formulation meets the efficacy requirements of European norm (EN) 12791, which is the most stringent available norm for surgical hand rub preparations. Even when modified with approximately 5% higher alcohol content, the formulations proved to be inferior to the reference of the norm when measured after 3 hours.

Objective: Because the high glycerol content of the formulations was suspected to negatively influence their efficacy, additional investigations were performed with varying glycerol content.

Methods: Modified formulations with higher alcohol concentration (mass instead of volume percentage) and lower glycerol concentration (0.725% instead of 1.45%) or without the addition of glycerol were evaluated for their conformity with the efficacy requirements of EN 12791, which demands noninferiority in comparison with a reference hand antisepsis procedure immediately and 3 hours after treatment on volunteers' hands.

Design: Randomized Latin-square design.

Setting: Microbiology laboratory of the Medical University of Vienna, Vienna, Austria.

Participants: Twenty-five healthy volunteers.

Results: Reducing the concentration of glycerol or omitting it completely rendered both WHO formulations noninferior to the reference, both immediately and 3 hours after surgical hand antisepsis.

Conclusions: Both WHO-recommended formulations meet the efficacy requirements of EN 12791 by increasing their alcohol concentrations by 5%, prolonging their application to 5 minutes and reducing the glycerol concentration to 0.725%.