Final answer:
Transmission-based precautions should be used when a patient has been diagnosed with infectious respiratory illnesses like influenza. These precautions are necessary to prevent the spread of the disease to others.
Step-by-step explanation:
Transmission-based precautions should be used when a patient has been diagnosed with infectious respiratory illnesses like influenza. These precautions are necessary to prevent the spread of the disease to others. They include measures such as isolating the patient, using personal protective equipment, and practicing proper hand hygiene.