The Positive Side

Summer 2013 

Sex and the Serodiscordant

Headlines about how a low viral load can cut the risk of HIV transmission lead many to wonder: “What do these findings mean for people living with HIV? And how do they affect my sex life?” CATIE’s James Wilton offers some answers.


Antiretroviral treatment has evolved dramatically since it first became available in 1996. Newer medications are more potent, less toxic and easier to take than ever before. With ongoing care, not only can people with HIV now expect to live almost as long and as healthily as people who are HIV negative, but recent research confirms what many scientists have long suspected: Treatment can dramatically reduce the risk of passing HIV to a sex partner. In a landmark study known as HPTN 052, HIV transmission was cut by 96% among heterosexual serodiscordant (positive/negative) couples if the HIV-positive partner was on treatment. So we now know that treatment can improve the health of people living with HIV and prevent HIV transmission.

These findings are changing the face of HIV and their significance is having a positive impact on many people living with the virus. John McCullagh, the publisher of—an online magazine by and for people living with HIV—and a member of CATIE’s board of directors, explains: “Having an undetectable viral load boosts my self-esteem and gives me a great sense of well-being. Apart from keeping me healthy, it lessens the burden of me worrying about transmitting HIV to someone else. It reduces the shame and fear of infecting others and this has had a positive impact on my life.”

Although successful treatment doesn’t eliminate the risk of transmission, our new knowledge means that undetectable HIV-positive people and their partners can worry less about transmission, especially if they also use condoms. Given that condoms aren’t always foolproof, an undetectable viral load can offer an extra layer of protection in case a condom breaks or slips off. Some people are even choosing to not use condoms; however, the decision to have sex without a condom is an important one and needs to be made with a solid understanding of the evidence and risks.

You Ask, CATIE Answers

Navigating what science has to say about treatment, viral load and HIV transmission can be challenging, and therefore simple answers are difficult to come by. What we do know is this:

  1. Antiretroviral treatment—when taken every day, as prescribed—can over time lower a person’s viral load to undetectable levels.
  2. A lower viral load in the blood generally means a lower risk of HIV transmission.

Beyond these basics, the information gets more complex and there are no cut-and-dried answers. Let’s look at some of the questions many people with HIV are asking:

How much does antiretroviral treatment reduce the risk of HIV transmission?

The HPTN 052 study showed that the risk of HIV transmission can be reduced by up to 96% for people living with HIV who are (a) in heterosexual relationships, (b) have mostly vaginal sex, (c) go regularly for adherence counselling, viral load tests and STI (sexually transmitted infection) screening, and (d) receive free condoms and regular HIV prevention counselling. But it is not clear if this dramatically reduced risk would be the same for couples in the “real world” (outside of a clinical trial) who may not have access to these services or for couples who mostly have anal sex—namely, gay men and other men who have sex with men. It is expected that treatment has an effect but to what extent we don’t yet know.

[UPDATE: In March 2014, a preliminary analysis of an ongoing study (the PARTNER study) reported the first direct evidence that treatment can significantly reduce HIV risk through anal sex in gay men.]

What is the risk of HIV transmission if my viral load is undetectable?

It’s impossible to give a precise answer, but the general consensus is that the risk is not zero. That is because HIV is still present in bodily fluids even when a person’s viral load is undetectable. (Undetectable does not mean that there is no virus in the blood, but rather that there is so little HIV present that available tests cannot detect it.) Also, research has found that when HIV is undetectable in a person’s blood, there can sometimes be detectable (although lowered) levels of HIV in their rectal fluid, semen or vaginal fluid. This is concerning because it may increase the risk of HIV transmission, even when the blood viral load is undetectable.

Even so, the risk of transmission from vaginal sex in serodiscordant couples is likely very low under the following conditions:

  • the viral load has been undetectable for at least six months;
  • HIV medications are taken as prescribed;
  • the HIV-positive partner goes for viral load testing regularly; and
  • neither partner has an STI.

However, it can sometimes be challenging to ensure that neither partner has an STI. Because STIs can increase the risk of HIV transmission and some STIs may be symptom-free, screening and treatment for all STIs by both partners is important. For those in casual sexual relationships, consistent use of condoms combined with regular screening and treatment for STIs can help keep the risk of HIV transmission low.

What about anal sex?

The biggest grey area is around anal sex. We know that, on average, the risk of HIV transmission through receptive anal sex can be 10 to 20 times higher than it is through vaginal sex. But that average includes people with high, low and undetectable viral loads. Is the risk still higher for anal sex when the viral load is known to be undetectable? Some experts think it might be but others, such as those at the British HIV Association, think it may be similar to the low risk for vaginal sex if the conditions listed above are met. In March 2014, interim analysis of the PARTNER study provided insight into the risk through anal sex when the viral load is undetectable.

These uncertainties are important to consider when negotiating safer sex. However, it is undeniable that when one’s viral load is undetectable (and other conditions are met), the risk of HIV transmission is dramatically lower. And this is having an effect on some people’s sex lives.

Pillow Talk

Open discussions can help sex partners agree on a safer-sex strategy. The topic of condom use is one that comes up often. Stephanie Smith, from Gatineau, Quebec, who has been living with HIV since 2003, feels that talking openly with her partners has played an important role in having healthy sexual relationships and reducing the risk of transmission. “When I am in a new relationship, I tell my partner that I prefer using condoms,” she says. “I know the risk is really low when the viral load is undetectable, but there is still the chance of passing HIV. In my current relationship we use condoms all the time, but my previous partner really didn’t enjoy using them. Since my viral load was undetectable, we went to the doctor together and discussed the risks and options. Based on that discussion, we decided to stop using condoms.”

For John McCullagh, who has been living with HIV for four years, decisions around safer sex also depend on the risk he and his partners are willing to take. “When I’m having sex with another positive guy,” he says, “I generally prefer to dispense with condoms. But when I have anal sex with negative guys, I’m very reluctant to do so without a condom, even though I am undetectable. In such instances, using condoms and having an undetectable viral load helps reduce the risk of HIV transmission to a level I am comfortable with.”

Telling your sex partner about your HIV status can open the door to talking about safer sex, but doing so isn’t always easy. McCullagh hasn’t always had good experiences. “Every time I have sex with someone new, we negotiate the kind of sex we want to have. It’s a two-way street and we have to agree. It always starts with me disclosing my HIV status. Unfortunately, disclosure is difficult and doesn’t always go well. There is a lot of rejection and stigma.” He points out that “for some people living with HIV, this means that they either don’t disclose or don’t have sex at all.”

One strategy to reduce the risk of rejection is to disclose as soon as possible, before feelings have formed. Nick, who has been living with HIV for 10 years and has been undetectable since 2009, makes sure that prospective partners know his HIV status before they meet. “I am very upfront about my HIV status,” he says. “My online dating profile even says I am HIV positive. If a guy knows I am HIV positive before we meet up, there are no surprises and it reduces my risk of being rejected. It also means that he is probably more knowledgeable about HIV and open to talking about it. This makes it easier to discuss things like safer sex.”

Extra Measures

Whether or not condoms are used, there are several things that can be done to keep the risk of HIV transmission as low as possible when on treatment. The most important is to make sure the viral load in the blood is undetectable and stays that way. (In Canada, this level is normally below 40 or 50 copies per ml of blood.) Scientists and doctors generally agree that your viral load should be undetectable for six months or more to minimize the risk of HIV transmission. Taking your medications every day exactly as prescribed is critical to getting your viral load to an undetectable level and keeping it there. If meds are missed, the viral load can increase, drug resistance can develop—leading to the need to switch HIV drugs and resulting in fewer drug options in the future—and the risk of HIV transmission can increase. Getting your viral load tested regularly can help ensure that the meds continue to suppress HIV. All of these things are also important for staying healthy.

Stephanie Rawson is a young HIV-positive woman who lives with her HIV-negative husband in Prince George, British Columbia. Her viral load is undetectable but she and her husband take extra steps to keep their HIV transmission risk low. “My partner and I use condoms when I am close to or on my period. This is because menstrual blood contains HIV even when the viral load is undetectable and can potentially increase our risk of transmission. I also make sure to take my meds regularly and get my blood work done every three months. If for some reason I forget to take my meds, we use condoms until the next time I get my blood work done, so that I know my viral load is still suppressed.”

Although having an undetectable viral load reduces the risk of HIV transmission, it is still possible for other STIs—such as gonorrhea, chlamydia, syphilis and herpes—to be transmitted. Whether it’s the HIV-positive or HIV-negative partner who has an infection, STIs increase the risk of HIV transmission, even when the viral load is undetectable. This means it’s important for both partners to look after their sexual health, get tested for STIs regularly and get appropriate vaccinations. Treating the STI as soon as possible and using condoms help to reduce the risk of STI and HIV transmission.

Nick combines having an undetectable viral load with additional strategies to reduce risk: “When I was single and with a guy who didn’t want to use condoms, I would minimize the risk by not ejaculating in my partner, using lots of lube and avoiding rough sex to reduce the chances of tearing. I also got tested regularly for STIs. I am now in a monogamous relationship with an HIV-negative guy. We are both STI-free and we use condoms most of the time, particularly if we’re engaging in sexual activities that could cause tearing. However, recently we didn’t use a condom and there was some tearing, so my partner started post-exposure prophylaxis (PEP). Now he’s thinking about starting pre-exposure prophylaxis (PrEP).”

Rawson feels that our new knowledge has had a positive impact on people’s sex lives. “People living with HIV have to deal with a lot of stigma, particularly when it comes to their sex lives,” she says. “Being undetectable allows my partner and me to have the sex we like to have and at the same time reduce our risk of HIV transmission. It has increased my sense of well-being and helps me feel less anxious and guilty about having sex.”

Nick believes he might not even be in his current relationship if it wasn’t for this new research. “Before me, my partner always said he would never date someone who is HIV positive because he was so worried about transmission. I think the understanding around undetectable viral load has put him at ease.”

The changing HIV landscape is good news for people living with HIV and their sex partners. Treatment turns out to be good not only for the physical health of people living with HIV but also for the health of their partners. By taking one’s meds consistently, getting viral load checkups regularly and looking after one’s physical and sexual health, the health of people living with HIV can be improved and the risk of HIV transmission reduced. Importantly, this helps reduce some of the fear, shame and stigma that some HIV-positive people experience when it comes to their sex lives and has a positive impact on their relationships as well as their mental and physical health. ✚


Starting Treatment

Most people with HIV start taking treatment at some point to improve their long-term health. For some people, HIV treatment can also be part of a plan to reduce the risk of passing HIV during sex (along with other strategies, such as condoms) and several treatment guidelines support this position. But the decision to start treatment rests with you, the person living with HIV. You need to be ready to start.

For the most up-to-date information on starting HIV treatment, call us at 1.800.263.1638 and discuss these issues with your doctor.

James Wilton is CATIE’s Biomedical Science of HIV Prevention Coordinator. He has an undergraduate degree in microbiology and immunology and is currently completing a master’s degree in epidemiology at the University of Toronto.