HIV Transmission Risk Remains During First 6 Months of Treatment

Andrew Mujugira, M.D.
Andrew Mujugira, M.D.

We have seen zero HIV transmissions among mixed-status couples when the HIV-positive partner is on treatment and has an undetectable viral load, according to recent studies. But what about when the positive partner has just started treatment? Terri Wilder spoke with Andrew Mujugira, M.D., who presented a poster on the risk of HIV transmission during the first six months of an HIV patient's antiretroviral therapy, at CROI 2015 in Seattle, Washington.

Please tell us about your study.

In Uganda about four in 10 new HIV infections occur in serodiscordant couples. This is a couple in which one partner is positive and the other partner is negative.

We know that giving the positive partner treatment with antiretroviral therapy can reduce the risk of transmission. But, before they are fully suppressed, before the amount of virus in the blood becomes below the limit of detection of the tests, they can still transmit the virus.

We followed 850 couples. We looked at three times periods: the time before they started treatment; during the first six months of treatment; and after six months of treatment.

These were heterosexual couples?

Yes, heterosexual serodiscordant couples. We found that the incidence of HIV was similar in the period during the first six months of treatment as before treatment. This is because people are transmitting the virus before they are fully suppressed. And so we suggest that during this period, the HIV-negative partner be given other prevention options like pre-exposure prophylaxis, or PrEP, and, obviously, condoms.

When you say pre-exposure prophylaxis, you're referring to tenofovir/emtricitabine (Truvada)?

Yes, Truvada prophylaxis, which is a combination of two drugs: tenofovir and emtricitabine. In the Partners PrEP study, in which these couples were enrolled, the negative partner was given pre-exposure prophylaxis. The analysis we present was only for those who were in the placebo arm. That is why the trial was still blinded.

"In the first six months of \[antiretroviral therapy\] there was a residual risk of transmission, which was about 2% per year."

Tell me about the results of your research, and what implications it might have for practice for medical providers.

We found that in the first six months of [antiretroviral therapy] there was a residual risk of transmission, which was about 2% per year. That was the same risk that we saw before they started treatment. So from a practice point of view, when you start the HIV-positive partner on treatment, make sure that you have prevention options for the negative partner. They should use condoms at all times, and offer the pre-exposure prophylaxis to the negative partner. And if it's a man, he should consider having male circumcision, in order to prevent/reduce his risk of getting transmission.

Results From Mujugira's Study
Treatment Status of Positive PartnerNNumber of Linked InfectionsPerson-Years of Follow-UpIncidence per 100 Person-Years (95% CI)
Not Yet on Treatment24931751.71
Less Than 6 months on Treatment36431681.79
Over 6 months on Treatment24201670.00

All of the couples that were in the study are from which country?

These are couples from Uganda and Kenya, in East Africa.

Is there any kind of uniqueness to the situation in those countries versus the United States, in terms of your research findings?

That's a very good question. About 5% of couples in Uganda are serodiscordant. The number in the United States would be much, much lower -- that's heterosexual couples. But among the MSM [men who have sex with men] community, there are quite a number of serodiscordant couples. We don't know how well combination [antiretroviral therapy] works for preventing male-to-male transmission, but we still think it should work as well as male-to-female transmission. Even in such couples, they should consider using pre-exposure prophylaxis (PrEP), until there is viral suppression in the positive partner.

Is it easy to access pre-exposure prophylaxis in Uganda? People have some challenges getting it in the United States.

Right. As you know, the United States is the only country that has rolled out PrEP. In Uganda, it's only available in research settings. We hope that we can get the ministry [of health] to include it in the prevention guidelines so that people can access it if they can afford to buy it from a drugstore or pharmacy.

In terms of getting the ministry of health to include it, is that going to be a challenging process?

Well, now we have the data. We have shown that it works. I think we need to make a better business case of the cost effectiveness of PrEP. Those studies are ongoing now. So, once the ministry can see, as we have demonstrated here, that there's still risk in the first six months of treatment, then we can make the business case of providing PrEP.

If PrEP were recommended in Uganda, how would it be paid for?

The majority of people in Uganda access health care through the public health care system. And it's nominally free. So it's provided by the government. What would happen is that they would access their local health center, where they usually get treatment; they would access it through there.

We also have PEPFAR [the U.S. President's Emergency Plan for AIDS Relief] in Uganda, which is paid for through the tax dollars of the American people, for which we are very grateful.

PEPFAR provides antiretroviral therapy to hundreds and thousands of Ugandans. So PEPFAR could be one way through which partner institutions with PEPFAR could provide PrEP. We already have the mechanism to give treatment. We can use the very same mechanism to give PrEP.

For the couples that were in this study, was the person living with HIV newly diagnosed?

The couples that we enrolled into the study had just known they were discordant for a median of about 0.4 years -- about five months. But as to when they actually got infected, we don't know that. We just know they recently knew they were discordant. That's why we were quite keen to prevent transmission to the negative partner.

Were all negative partners then given PrEP?

It was a placebo-controlled trial, in which one arm was randomized to tenofovir, alone; another arm to Truvada; and the third arm was a placebo arm. So the effect of tenofovir and Truvada in preventing HIV is compared to the placebo arm. We're doing these analyses after the end of the trial. So we're going back and looking at the data and saying: For those who took placebo, who are not on active PrEP, what was their risk of acquiring HIV from the positive partner? And they are the results I present here today; it was about 2% per year. About two people in every 100 acquired HIV.

"Once the HIV-infected partner is fully suppressed we observed no infections, none. So the critical period is the first six months of treatment."

The challenge here is that in the time before [the HIV-positive partners] actually become suppressed, you need to give the negative partner PrEP to protect them from acquiring HIV.

Any final thoughts about your study that are important for our readers to know?

Once the HIV-infected partner is fully suppressed we observed no infections, none. So the critical period is the first six months of treatment. And I think this is a testament to the fact that we need combination prevention. So, [antiretroviral therapy] for the HIV-infected partner, and PrEP for HIV-uninfected partner until they are fully suppressed, after which time we can take them off PrEP; so, using PrEP as a bridge to treatment.

View the full study poster.

This transcript has been edited for clarity.

Terri L. Wilder, M.S.W., is a director of HIV/AIDS education and training in New York City.