One of the best ways to prevent a coronavirus infection is to wash your hands with soap and water — and when soap and water aren’t available, public health experts say alcohol-based hand sanitizer is the next best option.
But just how effective are gels and sprays when it comes to getting rid of dangerous germs, such as the coronavirus? Here are seven things you should know about hand sanitizer.
1. Hand sanitizer kills germs but doesn’t clean your hands
Soap and water reign supreme when it comes to infection control, but believe it or not, soap and water do not kill germs; they remove them. The duo’s effectiveness boils down to the mechanics of handwashing.
The rubbing and scrubbing of soap between your palms and fingers creates friction that breaks down the structure of the bacteria and loosens the germs from your skin, explains Maryanne McGuckin, an infection prevention specialist and author of The Patient Survival Guide: 8 Simple Solutions to Prevent Hospital- and Healthcare-Associated Infections. When you rinse your hands under water, you wash those germs down the drain.
Alcohol-based hand sanitizers, on the other hand, do kill germs on the skin — most germs, anyway. Hand sanitizer is less effective at killing Cryptosporidium, norovirus and Clostridium difficile, all of which cause diarrhea, the Centers for Disease Control and Prevention (CDC) says. Scientists suspect hand sanitizer does, however, kill the coronavirus.
Hand sanitizers also don’t work as well if your hands are visibly dirty or greasy, and they may not remove harmful chemicals such as pesticides and heavy metals like lead.
2. Sanitizer trumps soap and water in certain situations
Because handwashing — when done properly — is better at getting rid of germs and grime, hand sanitizer, for the most part, should be used as a backup to soap and water. “The time to use hand sanitizer is when you can’t get to a sink and some clean water and a clean towel,” says Elaine Larson, professor emerita of epidemiology at Columbia University’s Mailman School of Public Health and a scholar in residence at New York Academy of Medicine.
That said, the CDC recommends using hand sanitizer as a first choice in certain situations, such as before and after visiting a friend or loved one in a hospital or nursing home. (That’s why you’ll often see dispensers posted directly outside patient rooms.) A squirt of hand sanitizer on your way in and out reduces the likelihood you’ll introduce a dangerous bug or leave with one. It’s also a good idea to use hand sanitizer regularly when interacting with people who have weakened immune systems, Larson says.
3. Not all hand sanitizers are equal
To kill most disease-causing germs, the CDC recommends using a hand sanitizer that contains at least 60 percent alcohol. Anything less than that may not work as well “for many types of germs,” and could “merely reduce the growth of germs rather than kill them outright,” the CDC says.
When searching the shelves, you may come across hand sanitizers that contain benzalkonium chloride instead of alcohol. These products, however, are not recommended by the CDC, since “available evidence indicates benzalkonium chloride has less reliable activity against certain bacteria and viruses” compared to alcohol-based sanitizers.
4. Sanitizing technique matters
Hand sanitizer works best when used correctly. Apply the recommended amount to the palm of your hand (make sure it’s enough to cover the entire surface of both hands) and distribute the sanitizer all over, paying special attention to the fingertips, “because that’s where you touch most other things,” Larson says.
Continue rubbing the hand sanitizer into your hands until your skin is completely dry — it should take about 20 seconds. This step is key, both Larson and McGuckin say.
“The alcohol works and it does kill the virus and most bacteria, but the problem that we have … is that people don’t use it appropriately for the given period of time,” McGuckin adds.