What are the three types of transmission-based precautions?

• A. Airborne, chemical, and radiant
• B. Droplet, vectorborne, dermal
• C. Airborne, droplet, and contact
• D. Contact, mechanical, optical

Answer: (C)

Three transmission-based precautions are airborne, droplet, and contact precautions. These are added to standard precautions to stop infections that require more than basic measures to prevent spread. Airborne precautions address pathogens that stay suspended in the air and can travel long distances; they require a negative-pressure room and respirators (like an N95) for anyone entering the room. Droplet precautions target larger respiratory droplets that travel only a short distance, so a private room or cohorting is used and people in proximity wear a surgical mask. Contact precautions protect against organisms spread by direct contact or contaminated surfaces, so gloves and a gown are worn, with a private room or cohorting as needed. Examples help anchor the concepts: airborne includes TB, measles, varicella; droplet includes influenza, mumps, rubella; and contact includes MRSA, VRE, C. difficile. Other categories like chemical, radiant, vectorborne, or dermal aren’t part of these three transmission-based precaution types.