Editor's note: This popular story from the Daily Briefing's archives was republished on May 28, 2020.

Hand sanitizer is flying off the shelves of U.S. stores as consumers race to protect themselves from the new coronavirus, but it turns out some of the most popular products—and some increasingly popular homemade recipes—don't meet CDC's criteria for killing the virus, ProPublica reports. 

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Hand sanitizers are flying off the shelves, but are they all effective?

While many Americans are slathering their hands with hand sanitizer to protect themselves, according to CDC, not all hand sanitizers will protect people from the new coronavirus.

To prevent the spread of the disease, CDC advises people to wash their hands, and when they can't do that, people should use hand sanitizer with at least 60% alcohol.

Data from Nielsen show hand sanitizer sales spiked 313.4% in the week ending Feb. 29 when compared to the same week in 2019. But, according to ProPublica, those sales include alcohol-free hand sanitizer, which CDC has noted are not effective against certain types of germs. Those products may reduce the growth of the germs but not kill them.

Some of the most popular hand sanitizer brands, including Germ-X and Purell, sell alcohol-free products that use benzalkonium chloride as the active ingredient instead of alcohol. And in some cases, it can be hard to tell the difference between the non-alcohol products and the ones that are more effective. ProPublica found that a search for "coronavirus hand sanitizer" on Amazon produces results for alcohol-free products that do not clearly state they don't contain alcohol.

For example, Purell Hand Sanitizing Wipes are made with an alcohol-free formula that uses benzalkonium chloride as an active ingredient. But the listing for the product on Amazon did not say it was "alcohol-free," according to ProPublica. What's more, the front of the packaging doesn't mention that they are alcohol free. But on the back, benzalkonium chloride is listed as an active ingredient in "small print," and the label mentions it's an alcohol-free formula, ProPublica reports.

And the product reviews suggest customers may not be aware that the non-alcohol products are less effective, according to ProPublica. For instance, one five-star review of Purell Hand Sanitizing Wipes states, "Honestly these wipes were a life saver. Due to the coronavirus and me traveling to Vietnam, I bought a pack. … I used these on flights, utensils before eating and seats before sitting. It gave me [a feeling] of safety..."

According to ProPublica, Amazon had not responded to ProPublica's request for comment before publication.

DIY hand sanitizer recipes spike (and what people are making might not work)

Meanwhile, the shortage of hand sanitizer on shelves and online has led some consumers to create their own at home.

Some popular online recipes include combinations of alcohol and aloe vera gel, while others swap the alcohol for whiskey or vodka. However, the World Health Organization (WHO) has stated any hand sanitizer recipe should include 96% ethyl alcohol, the amount of alcohol in whiskey and vodka is inadequate against germs.

According to Robert Glatter, an emergency physician at Lenox Hill Hospital, "Usually, the proof is double the percentage of alcohol in a spirit. Vodka is only 80 proof, or 40% alcohol—you need at least 60% to effectively kill viruses and bacteria," he said.

Tito's Handmade Vodka recently tweeted a warning to consumers. "Per the CDC, hand sanitizer needs to contain at least 60% alcohol. Tito's Handmade Vodka is 40% alcohol," the company said.

In addition to being ineffective, if mixed incorrectly, handmade hand sanitizers can actually be harmful, according to CNN. For instance, store-bought sanitizers contain emollients to protect the skin from alcohol, but sanitizers made at home often don't contain these ingredients, according to Sally Bloomfield, a professor at the London School of Hygiene and Tropical Medicine. 

The best way to protect yourself from the new coronavirus

So what is the best way to protect yourself? Wash your hands, according to health experts. According to CDC, hand sanitizer may not work as effectively as it could otherwise if hands are visible dirty or greasy.

But if hand sanitizer is the only option, be sure to use a sanitizer that contains at least 60% alcohol, and use enough to cover both hands, including between your fingers and under your nails, CNN reports. Rub your hands until they're dry (Allen/Song, ProPublica, 3/6; Lee, CNN, 3/3; Pesce, Market Watch, 3/7; New York Times, 3/12; Smith et al., New York Times, 3/12).