While EV is predominantly spread by contact with blood and body fluids, there is some uncertainty about the potential for aerosol transmission. There is RCT evidence for respirators but not masks providing protection against non-aerosolized infections and an abundance of evidence that transmission of pathogens in the clinical setting is rarely unmoral. Where uncertainty exists, the precautionary principle (that action to reduce risk should not await scientific certainty) should be invoked and guidelines should be consistent and err on the side of caution.