Officially declared a pandemic by the World Health Organization on March 11, 2020,1 SARS-CoV-2 remains a significant threat worldwide. In addition to physical distancing measures, hand-hygiene practices continue to be crucial in limiting the spread of the virus.
Washing hands with soap and water for 20 seconds remains the standard recommendation.2-3 However, in circumstances where there is no access to soap and water, the use of alcohol-based sanitizers – containing a minimum of 60% alcohol – is advised.
There are many types of hand sanitizers currently available, including non-alcohol based and alcohol-based hand sanitizers. Health Canada warns against making homemade sanitizers as they could be ineffective or even dangerous.3
How does hand sanitizer work?
The alcohol in hand sanitizer destroys the protective outer layer of viruses, making them unable to infect human cells.
Hand sanitizer is less effective when it is used for less than the recommended 30 seconds or if your hands are dirty, making it difficult for the sanitizer to penetrate through the dirt and grease.
Although there are alcohol-based hand sanitizers available that have a lower concentration of alcohol, it is recommended that you use hand sanitizer with at least 60% alcohol, which have a greater effectiveness.2
What is the most effective way to use hand sanitizer?
You should apply the hand sanitizer to the palm of your hand, making sure to spread and rub over every surface of your hand, continuing to do so until your hands are dry.4
It is important to use a sufficient amount of hand sanitizer to completely wet both hands. A recent study found that 3mL was enough to effectively cover both hands with sanitizer, however those with larger hands needed to use even more.5 To make this a little easier, that means – depending on the size of your hands – you should be using at least more than half a teaspoon of hand sanitizer to effectively disinfect your hands.
How effective is hand sanitizer against SARS-CoV-2?
A recent study investigated the effectiveness of the WHO-recommended hand rub formulations against the SARS-CoV-2 virus.6 The researchers reported that these formulations were able to effectively inactivate the virus. They also demonstrated similar effects when testing the formulations against SARS and MERS coronaviruses.
The researchers then also went on to examine whether the individual active ingredients in these WHO-recommended hand rub formulations were effective at inactivating the SARS-CoV-2 virus. These active ingredients are also the same ingredients present in commercially available hand sanitizers. The researchers reported that both ethanol and 2-propanol sufficiently reduced the amount of virus present after a period of 30 seconds.
- World Health Organization. WHO Director-General’s opening remarks at the media briefing on COVID-19: 11 March 2020 [cited 2020 Apr 8] https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19—11-march-2020
- Centers for Disease Control and Prevention. Show me the science: When and how to use hand sanitizer in community settings. Available at: https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html
- Health Canada. Hard surface disinfectants and hand sanitizers (COVID-19). Available at: https://www.canada.ca/en/health-canada/services/drugs-health-products/disinfectants/covid-19.html
- Kampf G, Reichel M, Feil Y, Eggerstedt S, Kaulfers PM. Influence of rub-in technique on required application time and hand coverage in hygienic hand disinfection. BMC Infect Dis. 2008;8:149.
- Walter Zingg, Tamas Haidegger, Didier Pittet. “Hand coverage by alcohol-based handrub varies: Volume and hand size matter.” Am J Infect Control 44 (12): 1689-1691. Published: 1-Dec-2016. DOI: 10.1016/j.ajic.2016.07.006
- Kratzel A, Todt D, V’kovski P, Steiner S, Gultrom M, Thao TTN, et al. Inactivation of severe acute respiratory syndrome coronavirus 2 by WHO-recommended hand rub formulations and alcohols. Emerg Infect Dis. 2020 Jul https://doi.org/10.3201/eid2607.200915
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