Hand hygiene is one of the pillars of infection control. It was recognized as far back as the nineteenth century as essential to prevent the spread of infections in hospitals – even before it was understood that microorganisms were responsible for causing diseases.
Although we have known for well over a century how microorganisms – bacteria, viruses, fungi, protozoans and parasitic worms – can be transmitted via infected hands, the actual practice of hand hygiene has not been optimal, even among medical professionals.
New medicines such as antibiotics lulled people into a false sense of security even into the present century. Studies consistently found compliance with handwashing guidelines in hospitals was only about 50% and there was also a reluctance to use alcohol-based hand rubs because of doubts among medical staff about their efficacy compared to antiseptic soap.
Increasing concerns over antibiotic resistance in the early 2000s resulted in a fresh emphasis on basic hygiene measures for preventing infections. In 2009, WHO launched the global Save lives: Clean your hands initiative to promote improved hand hygiene in medical facilities. This led to the Five Moments for Hand hygiene guidelines and included instructions on the production of alcohol-based hand sanitizers for sterilizing hands in the absence of soap and water.
Among the general public, numerous surveys showed low levels of awareness of the need for hand hygiene, particularly after using washrooms. A study conducted by Initial in 2015 found fewer than 50% washed their hands after using the toilet and an observational study of food handlers found only 14% complied with standard hand hygiene practices for food safety.
COVID-19 pandemic and hand hygiene
Today, after a year of the COVID-19 pandemic, virtually everyone in the world is aware of the need for hand hygiene to help prevent the spread of COVID-19. The WHO and governments have heavily promoted the need for regular hand-cleaning to prevent transmission to surfaces by infected people and from contaminated surfaces. Respiratory droplets are emitted by both gentle and vigorous air flows from the respiratory system: breathing, talking, coughing, sneezing, singing and shouting.
The demand for hand sanitizer surged in 2020 and it’s now ubiquitous at the entrance to buildings and in homes. Distilleries around the world changed production from drinks to hand sanitizer and chemical industries, perfumeries and breweries also switched production to fulfill the demand and respond to shortages in critical sectors. Google searches for “hand sanitizer” rose 100-fold in February 2020 as businesses and people sought supplies.
Should we wash or rub?
Washing with soap and water using the correct technique for 20 seconds is still the preferred method of cleaning hands. This is recommended by WHO and national health authorities. The action of the soap, water and rubbing every part of your hand for 20 seconds loosens any dirt and captures it along with any transient skin microorganisms in the foam. Then rinsing removes the dirt with the microorganisms and flushes them down the sink.
Enveloped viruses such as influenza (Orthomyxoviridae) and coronaviruses (Coronaviridae) have a capsule-like outer envelope composed of a lipid bilayer and a large number of proteins. Soap molecules have a hydrophilic (water-loving) end that is attracted to water and a hydrophobic (water hating) end that is attracted to lipids – such as those in the virus envelope. This chemical interaction is thought to enable soaps to break apart the virus envelope and neutralize these types of virus.
Frequent handwashing is not good for the skin, causing cracks that can hold microorganisms and make cuts worse. Dry and damaged skin can also flake, spreading any germs that it contains. Hands are more likely to host bacteria, which can live on and in the skin, than viruses, which cannot remain viable for long outside a living cell. But viruses can be picked up by touching the nose or mouth, respiratory droplets launched into the air or from contaminated surfaces.
When washing is not practical, or soap and water are not available, rubbing with hand sanitizer is a safe alternative. Hand sanitizers come in various forms and compositions, so what are the differences and the advantages of each?
Alcohol-based hand sanitizers
Alcohol-based hand sanitizers have long been known to have a greater antimicrobial effect than even antiseptic soaps – which are commonly used in healthcare settings. Their ease of use also encourages greater adherence to hand hygiene practices.
Enveloped viruses such as Zika, Ebola, coronaviruses (SARS, MERS) are effectively inactivated by sanitizers with recommended alcohol levels. A recent study found SARS-CoV-2 was inactivated by the WHO sanitizer formulations and also found that ethanol was effective at 30% and greater concentrations with a 30-second exposure. H1N1 flu and Hepatitis C are more resistant than the other enveloped viruses, while non-enveloped viruses such as norovirus, poliovirus and adenovirus show far higher resistance to alcohol-based sanitizers.
Comparisons of repeated exposure to alcohol disinfectant and a detergent over many days found the alcohol disinfectant caused less skin irritation and disruption to the skin barrier. The alcohol in hand sanitizers can, however, cause skin dryness with frequent use, so humectants (moisture retainer) or skin conditioners are added. Glycerin is the most common humectant used in sanitizers and cosmetic products. The more that is added, the greater the effect, but there has to be a balance between the effect on efficacy, the feel of the sanitizer and the humectant properties of the sanitizer. High concentrations slow down the drying time of the sanitizer and give it a sticky feel, especially when used repeatedly.
Most people will have experienced different formulations of alcohol sanitizer offered for public use at the entrance to supermarkets and other businesses. Some are very runny, drip off the hands and around the sanitizer station and evaporate quickly. Others feel sticky and leave a dirty residue on the hands. This is due to the different amounts of humectant and gel. The runny sanitizers are more likely to stay on the hands for a shorter time, making them less effective.
More importantly, however, glycerin lowers the antimicrobial activity of the alcohol in the sanitizer. The first WHO formula used a concentration of 1.45%, but this was found to give inadequate protection. The concentration of glycerine was halved, which enabled it to comply with efficacy standards (EN12791) for antimicrobial activity while still giving the skin some protection from the drying effect of alcohol.
Danger of alcohol poisoning
The worldwide rise in the use of alcohol-based hand sanitizers has also led to a large increase in alcohol poisoning in many countries. In October 2020, the National Toxicological and Forensic Sciences Institute in Spain reported 874 cases of intoxication from hand sanitizing gels, two-thirds of which were young children who drank it, inhaled it or got sanitizer in their eyes. There were 398 cases of poisoning reported to the National Poisons Information Service in the UK in 2020, an increase of 157% compared to 2019.
In the US, 15 people were hospitalized with methanol poisoning in Arizona and New Mexico after drinking tainted sanitizer. The FDA issued a recall for over 100 sanitizer products containing methanol, mainly originating from Mexico. Seven people died and two remained in a coma after a group of friends in the Russian republic of Sakha bought a 5-liter container of hand sanitizer when they ran out of alcohol at a party. The sanitizer contained 69% methanol, which has a lethal dose of 30gm and causes blindness with only 5–10 gm.
Non-alcohol sanitizers are not as well-known as alcohol-based ones and, in the US, the FDA only recommends the use of alcohol (ethanol and isopropyl alcohol). The FDA’s policies “do not cover the use of other active or inactive ingredients not otherwise mentioned in the guidance for use in hand sanitizer.” Unfortunately, these policies have not been updated throughout the pandemic.
There is good evidence, however, that other compounds are effective against not only the more well-known – pre-pandemic – bacteria, viruses and fungi, but also coronaviruses, including SARS-CoV-2. Quaternary ammonium compounds, including benzalkonium chloride (called quats or QATs) and chlorhexidine are detergents that have good antimicrobial properties. They are widely used as disinfectants and as ingredients in household products such as mouthwash. The EPA even lists them as approved ingredients for disinfectants suitable for use against SARS-CoV-2.
As SARS-CoV-2 is so new and infectious, few studies have been conducted on the virus itself rather than safer surrogate viruses such as feline or bovine coronavirus. A recent study of products containing quats found them to be effective against SARS-CoV-2 with short contact times, which reflects real-life use. Benzalkonium chloride is also known to be non-toxic for use on skin, less irritating than alcohol and non-flammable. Like alcohol and detergents, quats are effective against enveloped viruses, but not so effective against non-enveloped viruses.
A big advantage of quats is their persistence on the skin and surfaces after application. A study found benzalkonium chloride had good antibacterial activity on the skin up to four hours after application (the study only tested up to four hours), while an alcohol sanitizer showed little effect only one hour after application.
So which is better?
Both types of hand sanitizer can provide an effective and convenient product for killing or inactivating microorganisms, as long as they are used properly – which means using the right quantity, covering the hands properly and with the right length of time on the skin for alcohol-based formulae.
Even with sufficient alcohol concentration, the other ingredients can affect the effectiveness of alcohol-based sanitizers. The formulation can make them too runny, too sticky and less effective in antimicrobial activity. Alcohol is a fire hazard and also a poisoning hazard, especially for small children who may be able to consume toxic quantities from larger containers.
Non-alcoholic sanitizers are a viable alternative to the ubiquitous alcohol-based products. They are as effective against microorganisms, but have the advantage of providing longer-lasting protection on the skin, are kind to the skin and are safer overall. They can also reduce the pressure on supplies of alcohol.
Visit our hand hygiene hub to find out more about the solutions your business can put in place to help make visitors and staff feel hygienically safe.
Read more about people’s preferences when it comes to hand sanitizer and what they expect businesses to provide in public spaces – Hand sanitizers: essential protection or another COVID-19 myth?