>> jason lloyd. >> reporter: he doesn't have h.i.v.to stay that way, back in january, he was about to start taking what's called "prep"-- "pre-exposure prophylaxis." it's a daily dose of the drug truvada that will greatly reduce his chance of infection if he's exposed to h.i.v. >> there is always in the back of my head when i go to get tested, is the test going to be. is the test going to come back positive? because i do have risky activity, although it might be low risk. still risky. >> reporter: truvada was approved as a prevention tool by the f.d.a. in 2012. despite its proven ability to prevent h.i.v., it's been very controversial, and hasn't been widely embraced elsewhere. some fear those who take it will engage in riskier behavior, though there's very little evidence of that occurring. right now, an estimated 6,000 people in san francisco are taking truvada for h.i.v. prevention, and jason lloyd is joining their ranks. >> so i'll start taking tonight. so, we'll see. >> reporter: of course, truvada is for those who are uninfected.

lloyd bridges wet suit. i'll be ready. >>> in the meantime speaking of hot and grilling, jason chaffetz is the chairman of the house oversight be grilling comey later on today. when you heard him a couple of days ago with his 15 minute statement, it sure sounded like he was presenting the case to suggest charges and then he made a turn and were you as shocked as lot of people? >> i was. i mean, listen to the fact pattern laid out by the director comey and clearly, hillary clinton lied, miss led the american public, put people in jeopardy, took classified information and put it in a nonsecure format. anybody else out there, they would already have handcuffs on them and be in jail. yet, he came to the conclusion not to prosecute. that's the disconnect. >> director comey, one of the things he said, carelessness, negligence. you wanted to get an answer as to what the difference is. he frequently referred to intent. do you think you'll get a sufficient answer what is the difference between carelessness and negligence? >> that's what we want to understand, they're synonymous. look at the statute, the law, it's crystal clear. certa