~action taken to prevent disease, especially by specified means or against a specified disease.
What is PRE-EXPOSURE PROPHYLAXIS (PrEP)
~to PREVENT or CONTROL the spread of an infection or disease.
PRE-EXPOSURE PROPHYLAXIS (PrEP) for HIV
https://www.aids.gov/hiv-aids-basics/prevention/reduce-your-risk/pre-exposure-prophylaxis/
http://apps.who.int/iris/bitstream/10665/197906/1/WHO_HIV_2015.48_eng.pdf
https://www.aids.gov/hiv-aids-basics/prevention/reduce-your-risk/pre-exposure-prophylaxis/