One of the best ways to fight Covid-19: Wash your hands

It’s a top defense — and you’re probably doing it wrong.

With Covid-19 cases in nearly 50 countries, and the World Health Organization’s risk assessment now at the highest level, there’s never been a better time to brush up on one of the easiest ways to avoid the spread of infectious disease: proper hand hygiene.

Everyone from the WHO to the US Centers for Disease Control and Prevention has repeatedly emphasized hand-washing (or hand sanitizer if water and soap aren’t available) as a way to prevent the spread of the new coronavirus.

Dozens of studies show hand-washing can prevent life-threatening diseases, and even save lives. Reviews of the research, looking at the impact of hand-washing on respiratory diseases, have found the practice cut infections by around 15 to 20 percent.

And it’s not just respiratory diseases like Covid-19: In a 2008 review of the research, researchers looked at some of the best evidence for diarrhea-causing illnesses; they found that stringent hand-washing protocols, on average, reduced incidents of diarrhea by 29 percent in high-income countries and 31 percent in low- and middle-income countries.

Those decreases matter: More than 2,000 children die from diarrhea-related diseases every day, and respiratory diseases such as pneumonia kill millions every year.

Hygiene interventions can also reduce the number of sick days in schools. In a study of elementary school students in Denmark, researchers required the children to use hand sanitizer three times a day. Compared to the year before, there were 66 percent fewer schoolchildren with four or more sick days and 20 percent more with zero sick days.

”There’s more science behind hand hygiene than there is for other forms of infection control,” says Elaine Larson, associate dean for nursing research at Columbia University.

You’re probably not doing it right

A study in the Journal of Environmental Health found only 5 percent of Americans wash their hands properly. Although the CDC recommends 20 seconds of hand-washing, people on average wash their hands for about six seconds.

Obviously, hand-washing isn’t going to prevent disease if people aren’t doing it right. Here are four tips for proper hand-washing, from Larson and the CDC:

1) Wash your hands for at least 20 seconds. The amount of time spent hand-washing is important, Larson explains, to thoroughly cover and scrub every surface of both hands. To do this right, the CDC provides a step-by-step guide: Wet your hands with clean water, lather soap on every surface, scrub your hands together for at least 20 seconds, and rinse before drying. If you need a timer, the CDC recommends humming the “Happy Birthday” song from beginning to end twice.

2) Wash your fingertips and under your nails. “If you think about it, most of the touching and most of the germs are on your fingertips and maybe under your fingernails,” Larson says. “That’s a part of the hand that’s often skipped when people wash their hands.”

3) Wash your hands after every trip to the bathroom, blowing your nose, coughing, or sneezing, and before eating. Even if you think you didn’t get anything on your hands, wash them. There are always germs on your hands, and, at the very least, the bathroom is a convenient place to make sure some of those germs are cleaned off.

4) Wash your hands quickly after coughing, sneezing, or dealing with sick people. A previous study co-authored by Larson found that the flu virus can survive on hands and other surfaces for five to 10 minutes before it dissipates. During that time frame, people risk contaminating others as long as they don’t wash their hands.

There’s plenty of evidence to back it up: Dozens of studies show hand-washing can prevent life-threatening diseases, particularly in developing countries. And cleaning one’s hands doesn’t just reduce the spread of disease, it can save lives.

Don’t touch your face, particularly your mouth, nose, or eyes

We don’t yet know how exactly how SARS-CoV-2 — the virus that causes the Covid-19 disease — spreads, but we do have a lot of data on how MERS, SARS, and other respiratory viruses move from person to person. And that’s mainly through exposure to droplets from coughing or sneezing.

When an infected person coughs or sneezes, they let out a spray, and if these droplets reach the nose, eyes, or mouth of another person, they can pass on the virus, said Jennifer Nuzzo, an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security. In rarer cases, a person might catch a respiratory disease indirectly, “via touching droplets on surfaces — and then touching mucosal membranes” in the mouth, eyes, and nose, she added. There’s also emerging evidence showing that SARS-CoV-2 could spread through poop — known as the “fecal-oral” route of disease transmission.

That’s why it’s not just hand-washing that’s important; avoiding touching your nose, mouth, and eyes is, too. The CDC had these other, related tips for avoiding Covid-19:

• Avoid close contact with people who are sick.
• Stay home when you are sick.
• Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
• Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.
• Only use face masks if you have symptoms of Covid-19 or you’re a health worker or who are taking care of someone who is sick.

Wash instead of sanitizing whenever possible

As for hand sanitizer, Larson says it’s important to know that sanitizers are only active as long as they’re on your hands. So even if it makes your hands feel annoyingly wet, keep the sanitizer on for at least 10 seconds.

A multiyear study from the University of Michigan found that requiring students in residence halls to use surgical masks and alcohol-based sanitizers could reduce the spread of flu-like symptoms by up to 75 percent. Importantly, the study found masks alone played no statistically significant role, indicating that the hand sanitizer was responsible for the results.

On the question of whether to hand-wash or sanitize, there’s a simple solution, according to the CDC: Hand-wash on most occasions and use an alcohol-based sanitizer when water and soap aren’t available. Larson says that, for the typical healthy person, that should cover most hygiene needs.

”Hand-washing is better for cleaning off stuff,” Larson says. “If you have sputum, or if someone coughs, or if you have vomit, crap, or urine on your hands, soap and water are better cleaners. Alcohol is a better antiseptic. But in most cases, you can get the germs off your hands either way.”