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Antimicrob Resist Infect Control. 2018 May 16;7:65. doi: 10.1186/s13756-018-0357-6. eCollection 2018.

How long is enough? Identification of product dry-time as a primary driver of alcohol-based hand rub efficacy.

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1Institute of Hygiene and Applied Immunology, Medical University Vienna, Vienna, Austria.
GOJO Industries, Inc., One GOJO Plaza, Suite 500, Akron, OH 44311 USA.
3Center for Biofilm Engineering at Montana State University, Bozeman, MT 59717 USA.
4Department of Mathematical Sciences at Montana State University, Bozeman, MT 59717 USA.



The World Health Organization has called for the development of improved methodologies to evaluate alcohol-based handrub (ABHR) efficacy, including evaluation at "short application times and volumes that reflect actual use in healthcare facilities". The objective of this study was to investigate variables influencing ABHR efficacy, under test conditions reflective of clinical use.


The test product (60% V/V 2-propanol) was evaluated according to a modified EN 1500 methodology, where application volumes of 1 mL, 2 mL, and 3 mL were rubbed until dry. Statistical analyses were performed to investigate the relative influences of product volume, hand size, and product dry-time on efficacy, and hand size and hand contamination on product dry-time.


Mean log10 reduction factors (SD) were 1.99 (0.66), 2.96 (0.84) and 3.28 (0.96); and mean dry-times (SD) were 24 s (7 s), 50 s (14 s), and 67 s (20 s) at application volumes of 1 mL, 2 mL, and 3 mL, respectively (p ≤ 0.030). When data were examined at the individual volunteer level, there was a statistically significant correlation between dry-time and log reduction factor (p < 0.0001), independent of application volume. There was also a statistically significant correlation between hand surface area and dry-times (p = 0.047), but no correlation between hand surface area and efficacy (p = 0.698).


When keeping other variables such as alcohol type and concentration constant, product dry-time appears to be the primary driver of ABHR efficacy suggesting that dosing should be customized to each individual and focus on achieving a product dry-time delivering adequate efficacy.


ABHR; Application volume; Dose; EN 1500; Hand hygiene; Hygienic handrub

Conflict of interest statement

Study protocol was approved by the institutional ethics committee of the Medical University of Vienna. All participants gave informed written consent.DRM and RAL are employed by GOJO, Industries, Inc.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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