Who is most affected by new transmissions?
It’s mostly young men who have sex with men in their late teens to early 30s. And it’s more likely to be African Americans or Hispanics than whites.
Why do you think that is?
There are probably a number of historic reasons for this. In the past, black people have been less likely to be started on antiretroviral therapy through various prejudice, or because of systemic problems with health care in the United States, blacks being less well-insured than whites, and not necessarily having the same access to care. It’s more likely that if you’re a young black man who has sex with men, you’re more likely to have sex with someone who has an HIV infection and is not on antiretroviral therapy. But being a white man who has sex with men, you’re more likely to have sex with someone who, if they have HIV, is more likely to be on medications. There are studies that show it doesn’t matter what your race or ethnicity is, men who have sex with men generally have the same frequency of sex and number of sex partners. It’s not how often you’re having sex or the number you’re having sex with, it’s the probability of having sex with someone who has HIV and is not on therapy, or not controlled—doesn’t have their virus replication controlled on therapy.
It’s important to understand that on therapy these days, if someone’s viral load is what we call ‘undetectable,’ meaning that the number of virus replications is less than 200 copies of HIV on a per-milliliter of blood, if the viral load is less than that, one does not transmit their HIV infection to their sexual partner. There are no cases that have been reported where somebody with a viral load below that level has transmitted their infection to their partner, despite tens of thousands of reported sex acts without the use of condoms, of PrEP. Now we have an expression ‘U equals U: undetectable equals untransmittable.’ One of our major goals for HIV prevention in the developed world—or really, internationally—is to get people on antiretroviral therapy with an undetectable viral load, because then people with HIV can’t transmit infection to their partners.
How is PrEP (pre-exposure prophylaxis, drugs used to prevent the disease) changing HIV prevention? Is it having an impact on condom usage?
PrEP uptake is not as great as what we would like, particularly among the individuals at highest risk for acquiring the infection. The reasons for that are probably somewhat related to how medical care is provided in the United States, and the desire to perhaps not reveal that one is taking PrEP if one is a young gay man. They may not want their parents to know they’re on PrEP, so they won’t want to use their family health insurance plan. They may not want their friends to know they’re taking PrEP because it could out them as being gay, or perhaps friends could think somebody has got HIV infection because the drugs we use for PrEP are also drugs we use to treat people with HIV. There’s stigma associated with the use of these agents as well. Some parts of the country, people may need to travel a distance before they can find a provider who is knowledgeable about HIV prevention and is comfortable prescribing PrEP. There are barriers to the use of PrEP. We know it works when people take it. The data would suggest if people are taking four or more doses per week, they are almost 100 percent protected from acquiring HIV.
Now, I would assume, the data is not clear on this, but I’m assuming that people using PrEP are less likely to use condoms. The reason to use PrEP, in part, is to not have to use condoms. And the rates of sexually transmitted infections are going up, both in the U.S. and abroad, but that increase in rates of STIs predated the availability of PrEP. So, it’s not totally linked to PrEP, but it’s certainly possible the use of PrEP has helped propagate this increase in sexually transmitted infections. Obviously, it’s not desirable for there to be an increase in the rate of syphilis, gonorrhea, or chlamydia infections, but if, because of the availability of PrEP, if we have less HIV infection, because of the availability of PrEP, and the price we pay is a few more cases of these STIs, I think that’s a trade I would take any day.
I think we have to be comfortable understanding that may be a consequence.
What are we working on here at Penn?
We’re doing a lot of cutting-edge HIV research at Penn. In our prevention trial unit, we’re studying long-acting PrEP strategies, studying an injectable antiretroviral that may be effective when given as a couple of shots every couple of months, for HIV prevention. We’re also testing HIV vaccines. We’re testing the use of antibodies that we know neutralize HIV infection, and administering that also as a PrEP strategy. These are also compounds that can be given potentially every couple of months or, in newer versions being developed, maybe as infrequently as every six months. At Penn, we also have a very active HIV cure research program, where we’re studying ways to stimulate the virus out of its resting late state, and eliminate those infected cells with either immunologic strategies or sometimes gene therapy strategies, where we alter an individual’s cells in such a way that we make them not able to be infected by HIV. We’re at the very beginning of our testing strategies to cure people with HIV, we’re not anywhere close to being successful with that. But we’re trying to understand new approaches and whether these have the potential to lead to an HIV cure.
It sounds like the main obstacles are those high-risk groups and controlling the disease on a global scale.
That is the greatest obstacle. Where the research is right now in HIV, it’s in prevention and a cure. There are still new drugs being developed. There are a number of long-acting drugs being developed not only for prevention but treatment; I mentioned if you have HIV today you may be able to take just one pill per day. Probably five years from now, we will have combinations that can be taken once per week, once a month, once a couple months, or injections able to be taken every two-to-six months. There are implantable devices that can be developed where drugs will be put into a very thin straw, and the straw could be implanted in your arm. And they may last for a six-month period of time.
The treatments for HIV continue to improve, to become simpler and are now very well-tolerated. It’s really unusual for people to not be able to take HIV medications because of drug intolerance. The drugs we have available today [including PrEP] are really well-tolerated and easy to use.
What do you want people to know?
I think an important thing for people to understand is HIV is no longer a disease we should fear. And HIV-infected individuals should not be feared; that everybody who is at risk for HIV infection, which includes everybody who is sexually active, should get tested for HIV. And if infected, they should seek care. People should understand that despite all these advances, the battle is not over, and there is still work to be done. So, people should support the work in HIV in whatever way is possible or appropriate. And they should know there’s a lot of great work happening here on campus.
