- Researchers say washing your hands with soap and water is more effective than hand sanitizers in fighting the flu.
- Their research indicated you need to rub your hands with the ethanol in hand sanitizers for 4 minutes to kill the flu virus.
- Experts say the best preventive measure is getting a flu shot during the fall months.
Flu season is kicking into action and we’re all out here with our hand sanitizer close by, feeling secure.
But here’s the rub: that hand sanitizer may need a turbo boost.
In a study published today in mSphere, researchers say that ethanol — the active ingredient in both liquid and wipe hand sanitizers — can fall short when trying to kill germs in mucus.
That means as we fight the flu this season, we will want to either rub that sanitizer into the hands for 4 minutes or replace it with a good old-fashioned hand washing with soap.
“Consumers should be aware that the effectiveness of liquid disinfectants can be reduced against infectious mucus, and should not overestimate the disinfecting effectiveness,” said Dr. Ryohei Hirose, a physician and molecular gastroenterologist who co-authored the study with Takaaki Nakaya, PhD, an infectious disease researcher at Kyoto Prefectural University of Medicine in Japan.
But Hirose was quick to point out the study isn’t just a warning. It’s guidance.
“We want readers to know that there is room for improvement in current hand hygiene regimen, due to the presence of situations where the disinfection effect is reduced,” he told Healthline.
Hirose suggests rubbing hands longer — up to 4 minutes — to help the ethanol penetrate the mucus. Why?
The researchers concluded that the influenza A virus remains infectious in wet mucus even after being exposed to an ethanol-based disinfectant for 2 minutes.
Fully deactivating the virus, they found, required nearly 4 minutes of exposure to the disinfectant.
So, is this necessary for everyone?
Not necessarily, says Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University in Tennessee.
Schaffner praised the study and its importance, noting that both the general public and the medical profession can learn from it.
“This is an exceedingly well-done study,” Schaffner told Healthline.
He points out that the researchers used an adequate sample size of infected mucus, on a microscope slide, to test the effectiveness of treatments.
“In vast instances, you and I do not have globs of mucus on them,” Schaffner said. “We usually only have traces of virus in small spots.”
That said, he believes this study as well as follow-ups that will come, are important information and worth understanding.
“Suppose our spouse or young child gets the flu,” he said. “The child becomes that snotty-nosed kid and you get it on you. Or you clean up used tissues and get it on you.”
When you have anything visible on your hands — or you’ve been coughing into them or being coughed on — it is wise to turbo-charge the cleaning with the long ethanol rub or, better yet, dive into a good long hand wash.
“I suggest people sing the ‘Happy Birthday’ song every time they wash their hands. It’s a good timer,” Schaffner said.
Hirose echoes the sentiment.
“From the viewpoint of mass transfer theory, we had predicted that the virus in mucus would be somewhat resistant to alcohol disinfectants. However, we found that the protective effect of mucus is stronger than expected and there may be room for improvement in current hand hygiene guidelines,” he said.
That’s where soap and water comes in.
“We were surprised that hand washing was more effective than expected, and reaffirmed the effectiveness of hand washing,” Hirose said.
Still, Schaffner said, there is no need to throw that hand sanitizer away.
Using it regularly — and perhaps taking a little more time — is effective action to take through flu season and other times of the year.
Knowing to do more at certain times is even better, he said.
Hirose hopes to conduct more research, looking closely at hand rubbing and exactly how much time works best to kill the flu virus.
“The primary purpose of hand rubbing is to spread liquid disinfectant throughout the hands/fingers. However, hand rubbing can greatly contribute to overcoming situations where the effectiveness of (hand sanitizers) is diminished. We are verifying the scientific significance of the act of hand rubbing in order to propose the best regimen, including hand-rubbing methods,” he said.
In the meantime, doctors from across the nation will meet in Washington, D.C., during the final week of September to discuss the upcoming flu season.
Schaffner, who will serve as a moderator at the event, said hand hygiene will be discussed and then shared back with the public as well as healthcare professionals themselves.
They’ll also most likely be reminding the public that the best preventive medicine is still the flu vaccine.
“What is fundamental in influenza prevention and is timely now is vaccination,” Schaffner said. “It’s not a perfect vaccine, but what we fail to remember is that even if you get the flu, you are going to have a less severe case. The data (on that) is strong and valid.”