With the flu and other viruses circulating, the majority of people have hand sanitizer close by.
In a study published in mSphere, researchers say ethanol — the active ingredient in both liquid and wipe hand sanitizers — can fall short when trying to kill germs in mucus. That means in the flu fight this season, either rub that sanitizer into the hands for four 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 stated.
Hirose suggests rubbing hands longer — up to four 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 two minutes.
Fully deactivating the virus required nearly four minutes of exposure to the disinfectant.
Researchers used an adequate sample size of infected mucus, on a microscope slide, to test the effectiveness of treatments.
“From the viewpoint of mass transfer theory, we had predicted the virus in mucus would be somewhat resistant to alcohol disinfectants. However, the protective effect of mucus is stronger than expected and there may be room for improvement in current hand hygiene guidelines,” Hirose 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.
“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.”