So I chose to pursue a career in science because I believed at some deep level in the transformative power of discovery that scientific discovery learning something new can transform our world as we know it and yet over my 35 years there's only been a few opportunities where I could really feel

how that is true and one of those moments is when I learned the results of our clinical trial that I've been working on for eight years that was aiming to prove that a medicine taken before and after sexual exposure would be effective and safe for preventing acquisition of HIV and so we knew that we were about to learn whether all of that work was leading to yet another failure in the HIV prevention field or whether we had discovered some new way of preventing

HIV. So I gathered in this windowless room in Bethesda on the NIH campus. Several of us had traveled in some cases from places as far as way as Peru to be there. We were sitting around a table with our study sponsors, the investigators, the statisticians, source maybe 10 or 15 of us and we walked through the data and we heard for the first time that people who had taken care of the virus were in the first place.

People who had taken the drug did not get HIV infected. There was a round of applause, they just they clapped. There was nothing to say, people were stunned. I think people realized that everything was different, that everything was changed.

Scientists are celebrating what they're calling a major breakthrough in the fight against AIDS. A new study finds taking a drug called truvada before exposure to HIV reduces the risk of infection and gay men by up to 73%.

This is the first time a study has been done that shows that taking a drug before exposure to HIV can prevent infection. I think that we are in an era now for the first time when we can foresee the end of the AIDS epidemic.

From the New York Times, I'm Michael Bavaro, this is the Daily. Today, Dr. Robert Grant developed a treatment that could finally solve the HIV crisis, why it hasn't. It's Wednesday, June 5th.

As I was graduating, I remember talking to the dean of students and he says, well, what do you want to do with your medical career? I said, well, I'm going to work on HIV research. He says, oh, goodness, Bob, don't do that.

Why?

Well, he said, by the time you're fully trained, the epidemic will be over. To this day, I don't know if he was overly optimistic about how long it was going to take for the epidemic to end or whether he was overly pessimistic about how long it was going to take me to be fully trained.

In either case, I just became really clear that this was okay with me. If the epidemic ended tomorrow, I would retire and go fishing and tell stories about how there was a deadly disease that was among us for a while and disrupted our connections and our sex life and killed people when they were young for no reason.

After years of doing research in the early 2000s into treating HIV, he turns his focus to trying to prevent HIV and the concept he comes up with is pre-exposure prophylaxis or prep.

Donald G. McNeil, Jr. has been covering HIV for decades, which means taking one pill of HIV medicine per day, a small dose, to prevent you from getting the disease.

I remember saying, well, the next big task here is a vaccine. We need a HIV vaccine and yet try after try, the vaccines for HIV were not proving to be effective.

That's when I think many of us became interested in the possibility that the same anti-rich viral drugs that were good for treatment could also be used for prevention.

So he puts together a trial and eventually gets funding for it from the federal government and the Bill and Melinda Gates Foundation.

Our initial proposal was to use a medicine called Tenoffivir. Tenoffivir is a drug that under the brand name Travada was already being used for HIV treatment.

He wanted to see whether or not it would work for HIV prevention. And the drug company that makes it was willing to donate enough doses for the trial.

At that point, we chose to study Travada for prep.

Dr. Grant got the impression that Travada would soon be out from under patent protection.

And what made you believe that? That it would be going off patent?

Well, it had been invented in 1985. There were colleagues, friends at Goliad, who said, you know, don't worry about it.

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