Coronavirus: How to wash your hands properly, according to an infectious disease expert

As America gets to grips with COVID-19, a lot has been said about the importance of hand washing. Keeping your hands clean can shield you from germ spread — although you should always wash your hands, not just in the midst of a virus outbreak.

But if coronavirus has taught us anything, it is that people have a lot of questions about hand washing.

How long does it take to wash your hands? How does hand washing affect germ spread? And what is the difference between hand soap and hand sanitizer?

We asked an expert so you don't have to.

First, a PSA: Hand washing is important, no matter what is going on in the world.

The habit may prevent 1 in 5 respiratory illnesses and 1 in 3 diarrheal illnesses, Brian Katzowitz, a spokesperson from the US Centers for Disease Control, tells Inverse. If everyone routinely washed their hands, millions of deaths could be prevented every year, scientists estimate.

To understand why keeping your hands clean is so important, Inverse spoke to Didier Pittet, professor at and director of the Infection Control Programme and WHO Collaborating Centre on Patient Safety at the University of Geneva in Switzerland.

Hand washing is the best way to prevent the spread of germs

“In Switzerland currently, we don't shake hands anymore; the way we did it during the Ebola season with the Ebola time in Africa,” Pittet tells Inverse. He notes that countries around the world will soon adopt this strategy — if they haven't already.

“The best and the most important strategy to prevent coronavirus spread and transmission is hand hygiene and social distancing,” Pittet says.

Wearing a mask is not necessary, Pittet says. The only situation in which you should wear a mask is if you are sick, and you know that you will have contact with other people.

Basic hygiene and social etiquette matter, Pittet says. This includes blowing your nose into a tissue, and then throwing the tissue into the bin right away, sneezing away from people around you, and staying away from public areas if you are sick.

But isolation and anticipating every sneeze isn't always possible. So hand hygiene remains paramount.

“Hand hygiene is the most important way to prevent the transmission of coronavirus.”

Does hand washing with normal soap fight off coronavirus?

“Soap and water hand washing is absolutely fine and will eliminate or remove the coronavirus and this is very efficacious,” Pittet says.

When you have access to soap and water, you should wash your hands using the appropriate technique, Pittet says. The CDC recommends washing your hands for 20 seconds at least. A short time to spare to protect yourself.

“In public toilets, in your home, anywhere you find; you can use soap and water hand washing, you don't need to use a medicated soap. Plain soap would be okay without any problem," Pittet says.

In hospitals and other healthcare settings, people may use alcohol-based hand rub instead of hand soap for more advanced protection, Pittet says. But a lot of the benefits from alcohol-based hand rub stems in part from the clinical setting in which it is used. Using alcohol-based hand rub is faster than hand-washing, achieving the same end with greater convenience. But there is a catch: These hand rubs tend to work best only when hands aren’t heavily soiled, greasy, or, indeed, dirty.

“This is the reason why in healthcare settings we of course prefer to use alcohol-based hand rub, unless the hands are soiled,” Pittet tells Inverse.

How often should I wash my hands?

“It typically depends on what you are doing,” Pittet says.

“It's not necessary to do it every hour,” he says — but that would definitely ensure you’re keeping a good hygiene habit.

But different environments call for more fastidious washing, he says.

“If you just touch the nose of your kids who are sick, you need to do it immediately after, and not wait for an hour until you do it," he says. The same, if not more, care should be taken when caring for elderly people, who are among the demographics most vulnerable to the COVID-19 virus.

According to the CDC, you should wash your hands:

• Before, during, and after preparing food and eating food
• After using the toilet
• After blowing your nose, coughing, or sneezing
• Before and after caring for someone at home who is sick with vomiting or diarrhea
• Before and after treating a cut or wound
• After changing diapers, or cleaning a child who has used the toilet
• After touching an animal, animal feed, or animal waste

Remember: Scrub the entirety of your hands, including your upper wrist (think palms, backs, fingers, under your nails), for at least 20 seconds. All in all, you might spend almost an hour of your day keeping your hands clean, Pittet says.

Is there a difference between hand soap and sanitizer?

There is a very clear difference, Pittet says.

When you use soap, you are washing the bacteria off your hands. That is not true of hand sanitizer.

“A soap is actually soap; any soap and water is actually removing the bacteria from your hands, and not killing the bacteria on your hands,” he says.

Alcohol hand rubs and hand sanitizers, by contrast, kill the germs on your hands. But they don’t clean the dirt from your hands, Pittet says.

The reason why comes down to the chemistry of soap itself. Soap is made of molecules known as surfactants. These molecules have a hydrophilic end, which is attracted to water, and a hydrophobic one, which is repulsed by water. When you wash your hands with soap, the soap pulls the dirt and bacteria off of your hands and combines it with the water, which carries it away from your hands and into the sink.

Alcohol annihilates the germs directly on your hands. It kills germs through a process known as denaturation: Alcohol molecules have fat-loving properties and use them destroy bacteria cells' fat-based membranes, essentially dissolving them while they are on your hands.

How and when should I use hand sanitizer?

Now that people are paying more attention to their hand hygiene, Pittet speculates that many will start using hand sanitizer on top of washing their hands. Before shaking hands, for example.

"It's very convenient. It's very appropriate. It's very efficacious to have your alcohol-based hand rub with you and to apply a little bit of hand rub on your hands," he says.

The appropriate amount to use at a time is "a palmful," Pittet says. According to the CDC, you can either rub the hand sanitizer into your hands till your skin is dry, or simply cover your hands with hand sanitizer and let it air dry.

According to a 2000 study in the Journal of Infection Control, researchers found that, across 16 elementary schools and 6,000 students, the introduction of gel hand sanitizer in classrooms was linked to a 20 percent reduction in school absences.

“Elementary school absenteeism due to infection is significantly reduced when an alcohol gel hand sanitizer is used in the classroom as part of a hand hygiene program," they write.

A 2007 study suggests hand sanitizer may be an easy win for children, and can be a good solution if schools don’t have a lot of access to water. But there’s not necessarily any difference between soap or sanitizer in terms of preventing illnesses spreading among students.

What hand sanitizer should I use?

David Berendes, an epidemiologist in the Waterborne Disease Prevention Branch of the CDC, tells Inverse that research alcohol content matters.

“Sanitizers with 60-95 percent alcohol are more effective at killing germs than those with a lower alcohol concentration or non-alcohol-based hand sanitizers,” Berendes says.

Still, alcohol-based hand sanitizers don’t kill all types of germs, including norovirus, some parasites, and Clostridium difficile, he says. Hand sanitizers also may not remove harmful chemicals from the hands, including pesticides and heavy metals, like lead.

“In healthcare we use alcohol rubs that contain more than 75 percent ISOpropyl alcohol, or more than 80 percent actual alcohol,” Pittet says.

The WHO has its own formulation, allowing for hospitals and pharmacies to make their own product in-house.

Can I make my own hand sanitizer?

“I will certainly not do it by myself in my kitchen,” Pittet says. He recommends not to make your own hand sanitizer.

That is because there are very specific parameters, like for a recipe, that should be respected — and are easy to get wrong, he says.

If there is a shortage of hand sanitizers in your area, it is more responsible to go to a pharmacy and ask for them to make it for you, he says. In the US, there is already evidence of a shortage and of price gouging, with some retailers trying to pawn sanitizers off to unwitting punters for up to $194 a pop, Reuters reports.

“You can just go and ask your pharmacy," Pittet says. "Any pharmacist can do it and it's not complicated.” It is what pharmacists and medical authorities do every time there’s a shortage, he says.

But just in case you are feeling crafty: We tried making our own hand sanitizer anyways, and you can read all about it here.