Effectiveness of hand disinfection

The effectiveness of hand disinfection describes its ability to inactivate or kill transient microorganisms (viruses, bacteria, fungi) on the skin. It is the single most important measure for interrupting chains of infection in medical, nursing, and everyday settings.

Specifications and Standards

The effectiveness of hand sanitizers is demonstrated in standardized test procedures and divided into defined spectrums of activity:

• Limited virucidal activity: Effective against enveloped viruses, for example influenza, corona, HIV, as well as hepatitis B and hepatitis C viruses.
• Limited virucidal PLUS: Effective against enveloped viruses and additionally against certain non-enveloped viruses, especially adeno-, noro- and rotaviruses.
• Virucidal: Effective against enveloped and non-enveloped viruses.
• Bactericidal and yeasticidal: Effective against vegetative bacteria and yeasts.
• Other effects: Information such as tuberculocidal, mycobactericidal or fungicidal must be indicated separately.

Factors influencing effectiveness

Effectiveness depends significantly on correct application and can be influenced by the following parameters:

• Apply to dry skin: Disinfectant dilutes on damp hands, drastically reducing its effectiveness. Hands must always be dry before use.
• Wetting technology: Complete coverage (palms, backs of hands, nail folds, fingertips, spaces between fingers, thumbs and wrists) is crucial.
• Exposure time: The product must keep the skin moist for the entire application time (until complete evaporation). Sufficient [something] is required for this. Dosage necessary.
• Dose: Three to five milliliters (depending on the manufacturer and hand size) or a hand-filling amount of the alcoholic preparation are required.
• Jewelry: Rings, wristwatches, artificial fingernails or nail polish prevent mechanical cleaning and germ reduction.

Guidelines of the KRINKO and WHO

The Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute (RKI) and the World Health Organization (WHO) specify key requirements for the effective implementation of hand disinfection.^{1 2}

The most important recommendations are:

• Three practical pillars of effectiveness: Hand disinfection is only effective if it is performed at the right time, with sufficient quantity, and with complete wetting of all hand areas.
• Note the indications: Hand disinfection should be performed at relevant moments in patient care, particularly before patient contact, before aseptic procedures, after contact with potentially infectious material, after patient contact, and after contact with the immediate patient environment. The WHO summarizes this as the "5 Moments for Hand Hygiene".³
• Adhere to the quantity and exposure time: The disinfectant must be dosed in such a way that all hand surfaces remain wet for the entire recommended contact time of the disinfectant.
• Rub all areas of the hands: Both hands must be completely wetted. The product cannot work in areas where it is not wetted.
• Ensure skin protection and skin care: Skin protection and care are essential components of effective hand hygiene. Damaged skin is more difficult to disinfect and is more susceptible to colonization by microorganisms.
• Avoid jewelry and artificial nails: Rings, bracelets, watches, piercings on hands and forearms, as well as artificial fingernails, hinder proper hand disinfection and increase the risk of gaps in coverage or germ reservoirs.
• Operate dispensers hygienically: Hand sanitizer dispensers should be installed and operated in such a way as to minimize contamination. Elbow-operated or touchless operation is hygienically advisable; the dispenser outlet must not be touched with the hands.

Distinction: Hand disinfection vs. hand washing

Hand disinfection and handwashing serve different purposes. Hand disinfection aims to specifically reduce microorganisms on the hands. Handwashing primarily removes dirt, organic material, and residues mechanically. Which measure is appropriate depends on the context, the degree of soiling, and the risk of infection.

In a medical context

Hygienic hand disinfection serves the purpose of targeted killing or inactivation of microorganisms on the hands. For hands that are not visibly soiled, an alcohol-based hand sanitizer is the preferred method in most clinical situations because it acts quickly, is practical, and achieves a higher reduction in germ count than handwashing with soap and water. Under test conditions, alcohol-based hand rubs achieve an average germ reduction of approximately 3.5 log10 after 30 seconds, which is roughly equivalent to 99.97 %. Handwashing with ordinary soap achieves a reduction of approximately 1.8–2.8 log10 after 30 seconds.⁴

Handwashing primarily serves the mechanical removal of visible dirt, organic material, and certain pathogens. It is especially necessary when hands are visibly soiled or when organic material such as blood, secretions, or excretions needs to be removed.

A special case is the potential contact with spore-forming bacteria such as Clostridioides difficile. Alcoholic hand sanitizers are not sufficiently effective against bacterial spores. In such situations, thorough handwashing is necessary for mechanical removal; depending on hygiene regulations, this can be combined with hygienic hand disinfection.

Frequent handwashing can irritate the skin, as it washes away skin lipids and natural moisturizing factors, potentially leading to irritation. Modern alcohol-based hand rubs often contain nourishing or emollient ingredients and, when used correctly, are usually gentler on the skin than repeated washing with soap and water.

In a private context

In everyday life, handwashing with soap and water is paramount. It mechanically removes dirt, everyday germs, and residues from the skin, for example, before eating, before preparing food, and after coughing, sneezing, or blowing your nose.

Hand disinfection can be a useful supplement when no washing facility is available, there is an increased risk of infection, or when providing care at home. In home care settings, a doctor should determine when additional hand disinfection is recommended.

In cases of visible soiling, gastrointestinal illness, or possible contact with spore-forming organisms, alcohol-based hand disinfection alone is not sufficient. Thorough handwashing remains essential in these situations. At the same time, excessive washing should be avoided, and the skin should be regularly moisturized.

Sources:

1. KRINKO/RKI: Hand hygiene in healthcare facilities. Recommendation of the Commission for Hospital Hygiene and Infection Prevention at the Robert Koch Institute.
   https://www.rki.de/DE/Themen/Infektionskrankheiten/Krankenhaushygiene/KRINKO/Empfehlungen-der-KRINKO/Basishygiene/Downloads/Haendehyg_Rili.pdf?__blob=publicationFile&v=6 ↩︎
2. WHO: WHO Guidelines on Hand Hygiene in Health Care. First Global Patient Safety Challenge: Clean Care is Safer Care. Geneva: World Health Organization, 2009.
   https://www.who.int/publications/i/item/9789241597906 ↩︎
3. WHO: Your 5 Moments for Hand Hygiene. Posters. World Health Organization.
   https://cdn.who.int/media/docs/default-source/integrated-health-services-%28ihs%29/infection-prevention-and-control/your-5-moments-for-hand-hygiene-poster.pdf ↩︎
4. WHO: Review of preparations used for hand hygiene. In: WHO Guidelines on Hand Hygiene in Health Care. First Global Patient Safety Challenge: Clean Care is Safer Care. Geneva: World Health Organization, 2009.
   https://www.ncbi.nlm.nih.gov/books/NBK144041/ ↩︎