The makers of Purell are pruning their marketing strategy after the Food and Drug Administration slapped the company with a warning letter that told it to knock off unproven claims that the hand sanitizer can prevent diseases like Ebola, norovirus and MRSA.

The letter came as the United States is bracing for one of its worst flu seasons in decades and worldwide concerns grow amid a coronavirus outbreak that has killed at least 100 people in China, where the outbreak originated.

The warning targets the ways Gojo Industries, Purell’s parent company, marketed its popular line of alcohol-based gels, foams and sprays in social media materials, blog posts and frequently asked questions on the product and corporate website. Some of the statements that drew the FDA’s ire outlined in the warning appear to have been removed from Gojo and Purell sites since the FDA sent its letter on Jan. 17.

The FDA called out claims on Purell’s website that the products were proved to “reduce student absenteeism by up to 51%” and another that touted Purell as a solution to germ-infested athletic environments, where it could help to reduce MRSA and VRE by 100 percent.

Elsewhere, the FDA pointed to several instances where the Akron, Ohio-based company hedged with language that acknowledged it was unaware of any testing done on hand sanitizer and Ebola but went on to describe how such viruses are easily killed by alcohol — Purell’s key ingredient — and how groups like the World Health Organization and Centers for Disease Control recommend using alcohol-based hand sanitizers during an outbreak.

Those claims, the FDA wrote, indicate Gojo intended for customers to use its products to eliminate Ebola, flu and other diseases despite there being no studies that prove such antiseptics can produce the results Gojo implied.

Gojo told The Washington Post it took immediate action after receiving the FDA’s letter.

“The letter was related to some of our marketing around PURELL® Hand Sanitizer on GOJO.com and through our social media platforms,” Samantha Williams, a senior spokeswoman for Gojo said in a statement Tuesday. “It is important to emphasize that the FDA letter was not related to the safety or quality of our products, or our manufacturing processes. ”

On a sniffle-filled airplane or a sweaty gym, a bottle of hand sanitizer can feel like a blessing. Sales reliably spike during flu seasons, and consumers’ reliance on hand sanitizer appears to be growing: Hand sanitizer was an estimated $2.4 billion market worldwide in 2017, and that figure is expected to more than double by 2024, according to MarketWatch.

Experts caution that while hand sanitizers are highly effective for killing certain germs on contact, consumers should understand the products don’t work miracles.

“These alcohol-based hand sanitizers can provide a level of protection, but just carrying it around in your purse all day and using it is not going to prevent you with coming into contact with people who might be infectious,” said David Dowdy, an associate professor of infectious disease and epidemiology at Johns Hopkins University’s Bloomberg School of Public Health. Dowdy told The Washington Post that people need to consider how they come into contact with those who are infected since hand sanitizer doesn’t provide long-lasting protection.

“If you were touching a shopping cart that someone coughing or sneezing and had the flu had used and you had used hand sanitizer before you touched your nose or mouth, it probably killed the viruses on your hand,” he said. “But, the alcohol evaporates very rapidly, so if five minutes later you touched a light switch in a bathroom that someone before you with the flu had touched, you wouldn’t be protected.”

Dowdy noted when it comes to suggestions that hand sanitizer can be effective against Ebola, hands aren’t the only part of the body people should be concerned about since the virus can be transmitted through any type of secretion from the eyes, nose, mouth or other orifice. While hand sanitizer is typically effective against viruses like cold and flu, Dowdy echoed the FDA’s caution that it’s impossible to say concretely how effective hand sanitizer is against threats like Ebola or coronavirus until its been studied.

“If you’re Purell, you don’t want to be making claims about something that hasn’t been proven,” Dowdy said.

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