Just like wearing a mask to "prevent" viral infections

Cloth or cotton gauze masks have been used since the late 19th century to protect sterile fields from spit and mucous [NOT VIRUSES] generated by the wearer. A secondary function was to protect the mouth and nose of the wearer from the sprays and splashes of blood and body fluids [NOT VIRUSES] created during surgery.

Literature reviews have confirmed that wearing a mask during surgery has no impact whatsoever on wound infection rates during clean surgery. A recent 2014 report states categorically that no clinical trials have ever shown that wearing a mask prevents contamination of surgical sites.

Masks do not slow or stop the spread of viruses. Lastest research shows masks turn droplets into finer droplets, allowing suspended viruses to hang in the air even longer and travel further. It's irrelevant because most of the viral particles are not suspended in droplets and pass freely through mask material.