New research calls into question current CDC and WHO guidelines for hand hygiene to prevent the flu. According to a recent study published in a journal by the American Society of Microbiology, 30 seconds of hand-rubbing with an ethanol-based disinfectant won’t deactivate the influenza A virus (IAV) when mucus is carrying it. Hand-washing, in contrast, does the trick — and faster.

What the Study Found

To come to this conclusion, researchers took 19 sputum samples from individuals (greater than 20 years old) diagnosed with an acute, upper-respiratory infection, whose mucus also tested positive for IAV. Researchers used this material to create infectious mucus and then applied it to human fingers. During in situ tests, the researchers attempted to recreate how patients’ infectious mucus adheres to medical staff’s fingers. For comparison, they performed the same test with IAV-infected saline. The study found hand-rubbing with disinfectant was much more effective at inactivating IAV in saline than in mucus. More than two minutes of hand-rubbing did not inactivate the mucus, but less than 30 seconds did for the saline.

Because current hand hygiene guidelines from CDC and WHO suggest 15 to 30 seconds of hand-rubbing with ethanol-based sanitizer is adequate, the study “suggests … current contact infection prevention and AHR regimens using EBDs are insufficient to prevent IAV outbreaks,” the authors explain. The researchers also tested hand-rubbing with ethanol-based disinfectant on dried mucus, which worked within 30 seconds because its gel-like properties were gone. Similarly, hand-washing completely inactivated the virus in the wet mucus within 30 seconds.

What the Study Means for Clinicians

As a result, the study authors make the most logical recommendation: Wash your hands after coming in contact with flu patients instead of just hitting the hand sanitizer station. Follow the same protocol that you would with a non-enveloped virus, they add.

Another takeaway? Practices for evaluating the effectiveness of disinfection methods could use some revision. According to the authors, such tests usually include liquids with low viscosity, which means they don’t accurately simulate the physical properties of infectious body fluids. So, disinfectants (and disinfection methods) approved with currently recommended processes might be ineffective on mucus and other, more viscous bodily fluids.