Mucus from patients with influenza A remained infectious even after rubbing with alcohol-based hand sanitizers, a small study in Japan found.
Results were much better for hand washing with an antiseptic soap, which rapidly inactivated influenza A virus in mucus. This study’s author explained that the physical properties of mucus protect the virus from inactivation with hand rubs. Until the mucus has completely dried, infectious [influenza A virus] can remain on the hands and fingers, even after appropriate antiseptic hand rubbing.
Both the CDC and World Health Organization recommend hand hygiene practices with ethanol-based disinfectants (such as hand sanitizer) for 15-30 seconds, but this study indicates that this disinfection time is insufficient when not-yet-dried mucus is on individuals’ fingers, and current standard procedures calling for alcohol hand rubs to prevent flu outbreaks are therefore not adequate.
Once infectious mucus dries, the group noted, it can be inactivated through antiseptic hand rubbing. But that can occur only if enough time elapses between contacts with infected patients for the mucus to dry. If there is "insufficient time or no time gap" between treating patients, "the risk of spreading [influenza A virus] to the patient to be treated next will be higher than expected." In these cases, the authors recommended antiseptic hand washing before touching the next patient.
To test the effectiveness of ethanol-based disinfectants, they mixed influenza A with mucus and applied it to the fingers of 10 human volunteers, in order to "reproduce the situation" where mucus from patients with influenza A "adheres to the fingers of medical staff." After 2 minutes, the virus in the mucus was still active, the authors said, though by 4 minutes, it was not. The virus was deactivated in 30 seconds with full handwashing with antiseptic soap, whether or not the mucus was dry.