Introducing CoreShieldz™ A Disposable Protective Stethoscope Barrier Every medical experience begins with a relationship: a doctor listening to and learning about a heartbeat. That moment, stethoscope to chest, is precisely why CoreShieldz™ was invented, because studies show that moment is potentially very dangerous for patients. Yes, dangerous. In a 2009 study, 78% of all stethoscopes were infected with MRSA, Staph or other microorganisms. Further studies have backed it up: Stethoscopes are often very dirty. Infection Protection Made Easy.