Get the latest news on integrase inhibitors, Truvada for PrEP, and HIV vaccine development.

It’s a thrilling time for doctors and scientists who are studying HIV. New medications have made it possible to contain the virus like never before, allowing people to live long lives while drastically reducing their risk of transmission. But what’s next?

The largest gathering of HIV doctors and scientists in the world wrapped up recently in Boston. Several big developments emerged from the Conference on Retroviruses and Opportunistic Infections (CROI). Here are five things that had attendees buzzing.

Integrase inhibitors are better tolerated than protease inhibitors, and one study showed that they are the best way to go for most patients. In a study known as ACTG 5257, using raltegravir (Isentress) as a first-line treatment proved more effective and better tolerated than atazanavir/ritonavir or darunavir/ritonavir when taken with tenofovir/emtricitabine (Truvada).

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Efavirenz (Sustiva) is the most commonly prescribed HIV medicine in the world and contains some of the above ingredients. But patients with transmitted drug resistance or psychiatric disorders and women who plan to get pregnant cannot take it. Many patients also complain that the drug gives them nightmares.

Often, efavirenz is prescribed along with Truvada in the form of a once-daily pill called Atripla.

“Everyone says once a day is critically important, but in ACTG 5257, the twice a day regimen did best, because tolerability trumped convenience,” said Dr. Joel Gallant, chair of the HIV Medicine Association.

Conference attendees focused on the Partner study, in which there were zero HIV transmissions after 30,000 sex acts between serodiscordant couples (a couple in which one partner has HIV and one partner does not). In the study, all of the HIV-positive partners had viral loads under 200 copies per milliliter. The 1,100 couples included in the study had vaginal or anal sex, and all of them had sex without condoms at least part of the time.

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None of the HIV-negative partners were taking Truvada for PrEP (a once-daily pill to prevent HIV infection), but all of the HIV-positive partners were on antiretroviral drugs. The study backed up the findings of a previous one, known as HPTN 052, which showed that antiretroviral medications not only decrease HIV’s ability to reproduce and destroy the immune system, but also greatly lower transmission risk.

“We can’t say the risk is zero, but it sure is looking close to zero,” Gallant said. “Treatment is the most effective form of prevention.”

Truvada for pre-exposure prophylaxis, or PrEP, is not only safe and effective, but also underprescribed, Gallant said. This is frustrating for HIV doctors, who have embraced PrEP for those who need it.

HIV doctors don’t usually see patients who do not have HIV, so they are not the ones who should be prescribing PrEP. Primary care physicians often do not know what Truvada is, or they are opposed to prescribing an HIV medication for someone who does not have HIV, fearing that it will lead to unsafe sexual behavior.

“I always use the example of a guy who comes in with syphilis or rectal gonorrhea,” Gallant said. “He’s telling you ‘I am at risk for HIV’ without saying it. If you don’t have a discussion about PrEP at that moment, and he becomes infected in six months, you have missed an opportunity to prevent HIV infection. I think that’s happening a lot.”

Someday, people with HIV may just get a monthly shot of their antiretroviral medications instead of taking their daily pill or pills. The same could hold true for PrEP.

A study presented at the conference demonstrated that an integrase inhibitor in development, known as GSK744, is effective for pre-exposure prophylaxis in female monkeys injected vaginally with the simian version of HIV.

Currently, PrEP must be taken daily in order to work properly. Opponents of the medication say a patient may forget to take their daily dose or use it off-label “as needed,” which can result in infections. An injectable form of GSK 744, which has been developed, would help ensure compliance.

Everyone would love to see an HIV vaccine, but don’t count on it anytime soon. “There are so many exciting things in HIV, but not much is exciting in vaccine development,” Gallant said.

The same goes for a cure. In an abstract he presented at the conference, University of Pittsburgh researcher John W. Mellors wrote, “Progress toward a cure of HIV infection will undoubtedly occur, but the challenge of developing and delivering effective and scalable therapies to most HIV-infected persons is a formidable one.”

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