No, no, no. You use a phantom of the opera type mask to conceal your identity, so they cant sue you for feeling them up while pretending to do CPR.
Or, you might use a
resuscitation mask which enables you to breathe into the patient's mouth without getting their kooties into your mouth or yours into theirs. The former is especially important if they have oral bleeding (knocked out tooth, eg) or vomiting (gastral backflow common in horizontal unconscious patients).
Hazards include hepatitis and HIV. And herpes, I guess, and colds, flu, glandular fever etc etc. Kooties, generally.