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Updated: Jan 19, 2026
A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens
Published on: June 7, 2017
Situations Leading to Reduced Effectiveness of Current Hand Hygiene against Infectious Mucus from Influenza
Ryohei Hirose1,2, Takaaki Nakaya3, Yuji Naito4
1Department of Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan ryo-hiro@koto.kpu-m.ac.jp tnakaya@koto.kpu-m.ac.jp.
Abstract:
Both antiseptic hand rubbing (AHR) using ethanol-based disinfectants (EBDs) and antiseptic hand washing (AHW) are important means of infection control to prevent seasonal influenza A virus (IAV) outbreaks. However, previous reports suggest a reduced efficacy of ethanol disinfection against pathogens in mucus. We aimed to elucidate the situations and mechanisms underlying the reduced efficacy of EBDs against IAV in infectious mucus. We evaluated IAV inactivation and ethanol concentration change using IAV-infected patients' mucus (sputum). Additionally, AHR and AHW effectiveness against infectious mucus adhering to the hands and fingers was evaluated in 10 volunteers. Our clinical study showed that EBD effectiveness against IAV in mucus was extremely reduced compared to IAV in saline. IAV in mucus remained active despite 120 s of AHR; however, IAV in saline was completely inactivated within 30 s. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the time required for the ethanol concentration to reach an IAV inactivation level and thus for EBDs to completely inactivate IAV was approximately eight times longer in mucus than in saline. On the other hand, AHR inactivated IAV in mucus within 30 s when the mucus dried completely because the hydrogel characteristics were lost. Additionally, AHW rapidly inactivated IAV. Until infectious mucus has completely dried, infectious IAV can remain on the hands and fingers, even after appropriate AHR using EBD, thereby increasing the risk of IAV transmission. We clarified the ineffectiveness of EBD use against IAV in infectious mucus.IMPORTANCE Antiseptic hand rubbing (AHR) and antiseptic hand washing (AHW) are important to prevent the spread of influenza A virus (IAV). This study elucidated the situations/mechanisms underlying the reduced efficacy of AHR against infectious mucus derived from IAV-infected individuals and indicated the weaknesses of the current hand hygiene regimens. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the efficacy of AHR using ethanol-based disinfectant against mucus is greatly reduced until infectious mucus adhering to the hands/fingers has completely dried. If there is insufficient time before treating the next patient (i.e., if the infectious mucus is not completely dry), medical staff should be aware that effectiveness of AHR is reduced. Since AHW is effective against both dry and nondry infectious mucus, AHW should be adopted to compensate for these weaknesses of AHR.
Insights
Ethanol-based disinfectants are less effective against influenza A virus in mucus until it dries. Antiseptic hand washing is more effective against mucus-contaminated hands, offering better protection against influenza virus transmission.
Area of Science:
- Infectious diseases
- Microbiology
- Public health
Background:
- Antiseptic hand rubbing (AHR) and washing (AHW) are crucial for controlling influenza A virus (IAV) outbreaks.
- Ethanol-based disinfectants (EBDs) may have reduced efficacy against pathogens present in mucus.
Purpose of the Study:
- To investigate the reduced efficacy of EBDs against IAV in infectious mucus.
- To elucidate the mechanisms behind this reduced efficacy and identify optimal hand hygiene practices.
Main Methods:
- Evaluation of IAV inactivation and ethanol concentration changes in patient mucus (sputum).
- Assessment of AHR and AHW effectiveness on mucus-contaminated hands in volunteers.
Main Results:
- EBD effectiveness against IAV in mucus was significantly lower than in saline.
- IAV in mucus remained active after 120s of AHR, while IAV in saline was inactivated within 30s.
- AHR was effective on dried mucus, and AHW rapidly inactivated IAV in both dry and non-dry mucus.
Conclusions:
- EBDs are less effective against IAV in non-dried mucus due to mucus's hydrogel properties hindering ethanol diffusion.
- Infectious IAV can persist on hands after AHR if mucus is not completely dry, increasing transmission risk.
- AHW is a more reliable method for IAV inactivation in the presence of mucus and should be considered to supplement AHR.
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