COVID-19 Resource Center
COVID-19 Resource Center
Source/Disclosures
Source: Healio Interview
Disclosures: Schaffner reports consulting for, receiving research funding and/or travel or conference support from companies and trade associations that are involved in soaps, sanitizers and handwashing, including the American Cleaning Institute, Diversey, Ecolab, GOJO Industries and the Sloan Valve Co.
December 16, 2020
3 min read
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Q&A: What is the best method for handwashing?

Source/Disclosures
Source: Healio Interview
Disclosures: Schaffner reports consulting for, receiving research funding and/or travel or conference support from companies and trade associations that are involved in soaps, sanitizers and handwashing, including the American Cleaning Institute, Diversey, Ecolab, GOJO Industries and the Sloan Valve Co.
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Health authorities in the United States and abroad have stressed the importance of handwashing to prevent the spread of SARS-CoV-2.

A recent MMWR report found that while hand hygiene practices have improved in 2020, less than 75% of Americans washed their hands after coughing, sneezing or blowing their noses and before eating at home and in restaurants.

Quote from Schaffner on soaps used for handwashing

Healio Primary Care spoke with Donald W. Schaffner, PhD, distinguished professor and extension specialist in food science at Rutgers University, to learn more about the importance of handwashing and hand hygiene tips to offer patients.

Q: Can we quantify how much hand washing cuts down on the transmission of viruses?

A: Unfortunately, we don't have data to clearly quantify how much of a difference handwashing makes in transmission of viruses.

What we do know about the transmission of COVID-19 is that the primary risk comes from being indoors with people who are unmasked and shedding the virus. We know that people do not need to be symptomatic to be shedding the virus. I think it is much more important to practice appropriate physical distancing and mask wearing first, and if you're doing that then worry about handwashing or using hand sanitizers.

Q: How long should people wash their hands, and what evidence supports that length of time?

The standard recommendation is for a lather time of 15 to 20 seconds. This does not include the time to wet the hand, supply soap or the time to rinse hands after lathering. It also does not count the time needed to dry hands after the hand wash.

Unfortunately, the evidence in support of this specific amount of time is not terribly strong. Based on an analysis of literature data that I did a number of years ago, the variation from study to study is far more than the variation from 15 vs. 20 seconds.

My general advice is to wash your hands when they're dirty, and lather long enough to get them clean looking and feeling.

Q: What soaps are most effective against viruses?

A: Although some people have been claiming on the internet that soaps just “pops” viruses, support for this in the scientific literature is weak. What we do know is that soaps work primarily by removing microorganisms including viruses from the hands, so microbes on the hands get washed down the drain with the water. The bottom line is that no soaps are generally any more effective than any others at killing viruses. There is evidence that antibacterial soaps are more effective against bacteria than plain soaps.

Q: Does the temperature of the water matter?

A: Based on research that we have done with bacteria, we did not see a difference between 60°, 80° or 100°F. The person-to-person variation between individuals is generally quite large in studies like ours. Other research on the effect of water temperature has shown similar findings. My advice is to use a water temperature that is comfortable, so that you can be sure to do a good job washing your hands.

Q: Overall, do people wash their hands correctly?

A: While it's difficult to define what would exactly be a “correct” hand wash, what we do know is that many people will not wash their hands with a lather time of at least 15 seconds. What we do know from some research that I've been involved with recently that has as yet to be published is that the more people try to wash their hands when they are supposed to, and the better they try to do, the more effective they are at reducing spread of microorganisms in the kitchen.

Q: What is the best method of washing your hands, and what is the simplest and clearest way to explain that method to patients?

A: My advice is to wet your hands, apply soap, lather for 15 or 20 seconds, rinse the soap off, and then dry your hands with a paper towel or with a clean cloth towel.

We also know that people have difficulty in understanding just how long that time might be, so you often hear the recommendation to sing the ABC song or to sing happy birthday twice.

I also want to add that if you are in a hurry, or if you don't have access to soap and water, or especially if your hands are not visibly dirty, use of an alcohol-based hand sanitizer is a very effective alternative. We know that these alcohol-based hand sanitizers are very effective against many kinds of bacteria. They are also very effective against the virus that causes COVID-19.