Does having an undetectable viral load mean that you can’t pass on HIV to your HIV negative partner?
The Swiss Statement
In January 2008 the Swiss AIDS Commission sparked an intense debate on how infectious people are when they are on HIV treatments, and on what the implications are for HIV prevention. The Commission issued a statement that “after review of the medical literature and extensive discussion (…) an HIV infected person on antiretroviral therapy with completely suppressed viraemia (or undetectable viral load) is not sexually infectious i.e., cannot transmit HIV through sexual contact.” Significantly they also went on to say that the above statement is valid as long as certain strict conditions are in place:
- The person adheres to antiretroviral therapy, the effects of which must be evaluated regularly by the treating physician, and
- The viral load has been suppressed (less than 40 copies /ml) for at least six months, and
- There are no other sexually transmitted infections
Some limitations in the Swiss statement
The Commission also adds a cautionary note and exceptions. After a few days or weeks of discontinued antiretroviral therapy, plasma viral load rises rapidly. There was at least one report of transmission during this rebound in the studies they looked at.
Also importantly, the Swiss report focused on heterosexual serodiscordant couples. It did not provide information about gay men or anal sex. We do not therefore know if the findings are valid in relation to people who have anal sex and men who have sex with men.
The Commission also focused on people who are in stable relationships; not on sex between casual partners. “People who are not in a stable relationship must protect themselves”, the Commission notes, “as they would not be able to verify whether their partner is positive or on effective antiviral therapy.” Some experts also caution couples that viral load can rise quickly for a number of reasons including non adherence to HIV treatments, having an STI, concurrent illness, vaccinations and emergence of drug resistance.
We have known for some time that suppressing HIV viral load significantly reduces the risk of HIV transmission. A question remains however whether it is premature to say it eliminates the risk. While this report is certainly good news, condoms remain the most effective means of prevention while these kinds of questions remain.
Advice from a local expert in sexual health
In our recent Sero Disco magazine we asked Dr Robert Finlayson, from Taylor Square Private Clinic who has twenty years experience in HIV and Sexual Health about his view on this issue.
“It’s been known for years that HIV infectiousness is related to HIV viral load, so that a person with a high viral load will be more infectious when having unprotected sex than someone with a low or “undetectable “ viral load.
“Undetectable” viral load means there are less than 40 copies/ml of HIV* in the plasma (the fluid part of blood), but the virus may still be in some blood cells, and even more often still be in semen (cum) and rectal mucous. This is why there could still be some risk when you have unprotected sex with someone whose viral load is “undetectable”.
The risk of transmitting HIV is much greater if there is any inflammation in the genitals, a sexually transmitted disease or trauma. Also, someone may have been “undetectable” at their last test but not have taken their pills 100% of the time since, so their viral load might be higher than it was when they were tested. Safer sex is still recommended even if your partner is “undetectable”.
Some couples are already using undetectable viral load without condoms to reduce their risk of passing on or getting HIV. However, much more research still needs to be done, to have a better knowledge of the risks involved. Tom, who is HIV negative and has been in a relationship with Greg (HIV positive) for fifteen years, saw Greg’s undetectable viral load as more of an added reassurance, rather than a replacement of condoms and safe sex. “(My) first couple of (HIV tests) were very stressful, especially the first time. But after that, it hasn’t worried me much at all and I just consider it a routine check. Safe sex, using condoms, obviously does work. Greg also takes HIV treatments and his viral load is undetectable, and that gives us an added sense of security, if we needed one.”
Persson (2009) in Men and women living heterosexually with HIV: Straightpoz study, reports some couples who practised unprotected sex were already drawing on similar understandings of “undetectability and reduced risk, with one difference being that they believed an undetectable viral load made a positive partner less infectious, rather than non-infectious as claimed in the Swiss statement.” Narratives like Lydia’s support her observations: ‘I’m lucky at the moment, touch wood, because my viral load is undetectable and my count is good, so there’s even less risk of passing it along’. Similarly, Mahmoud stated: ‘[A]t the moment because of my T-cells and my viral load is undetectable, so I’m pretty safe, you know’”. Persson adds: “It should be noted that in the case of all couples who practised unprotected sex, the positive partner was on treatments and had an undetectable viral load.”
In summary
If some serodiscordant couples have decided to take the risk of not using condoms and to rely on viral load they should certainly monitor their situation closely. Remember that an undetectable viral load decreases (and we cannot say it eliminates) the risk of passing on or getting HIV only if -
- You never miss a treatment dose
- Your viral load has been consistently undetectable over a six month period
- You and your partner are both certain neither of you has an STI (with or without symptoms)
Condoms, however, can take the stress out of all these uncertainties and are proven to be the safest way to avoid passing on or getting HIV.
*40 copies/ml is as low as the viral load test can detect.
- Persson, A., Richards, W., Barton, D., & Reakes, K., (2009) Men and women living heterosexually with HIV: Straightpoz study, Volume 2 (Monograph 1/2009). Sydney: National Centre in HIV Social Research, The University of New South Wales, p 39.
- Ibid
