June 18, 2014
In the past few years, a large body of evidence has emerged supporting the use of antiretroviral therapy (ART) as an HIV prevention tool. This evidence shows that effective ART can reduce the amount of virus (also known as viral load) in the blood and other bodily fluids to undetectable levels, which can significantly reduce the risk of sexually transmitting HIV.
This new knowledge may affect the choices people make when it comes to sex. Therefore, people living with HIV and their partners need to receive accurate and consistent information on the risk of HIV transmission associated with having an undetectable viral load.
Translating the available research findings into easily understandable messages can be challenging. Thankfully, experts in different parts of the world are reviewing the research and coming to a consensus on the level of risk.
The Quebec Ministry of Health recently adopted a consensus statement on viral load and HIV transmission risk. This statement was developed to inform the delivery of risk-reduction counselling and is the first of its kind in Canada to be adopted by a provincial health authority. (Recently, a group of Canadian scientists released a consensus expert opinion on this topic that was developed to inform the criminal justice system.) The Quebec statement adds to a growing list of similar statements from around the world, such as the position statement released by the British HIV Association (BHIVA) in 2013.
The Quebec consensus statement was developed by an expert sub-committee assembled by the Comité sur les ITSS (Committee on Sexually Transmitted and Blood-borne Infections), which is part of the Institut national de santé publique du Québec (Quebec's National Public Health Institute). The statement was initiated at the request of the Service de lutte contre les ITSS (Sexually Transmitted and Blood-borne Infections Health Unit) of the ministère de la Santé et des Services sociaux (Ministry of Health and Social Services) of Quebec.
The consensus statement was developed to update the Ministry's existing HIV risk communication tool entitled "Estimation du risque associé aux activités sexuelles" (Assessment of risk associated with sexual activities). This resource was created to help healthcare and social service workers provide risk-reduction counselling to clients.
To develop the statement, the sub-committee first conducted a review of the research on viral load and HIV transmission. Information from that review was then used to develop a consensus on the level of risk associated with different sexual activities when a person's viral load is undetectable.
Describing different levels of HIV risk is challenging. In general, risk can be expressed quantitatively (using numbers, such as 1%) or qualitatively (using risk categories, such as "low risk"). For the Quebec consensus statement, the experts used the same risk categories as those previously used and defined in the Ministry's HIV risk communication tool.
The Expert Consensus concluded that the risk of HIV transmission from condomless vaginal sex is reduced from "high" to "negligible or very low" when the following conditions are met:
Although the literature review identified a lack of data about anal sex, the experts concluded that the HIV transmission risk through this type of sex is also reduced from "high" to "negligible or very low" when the above conditions are met. (Note: Since this literature review was conducted, a preliminary analysis of an ongoing study has reported the first direct evidence that ART can reduce the risk of transmitting HIV through anal sex). Similarly, the HIV transmission risk through oral sex is "negligible or very low" when the above conditions are met.
When using qualitative categories to describe HIV risk, it is important to explain how the categories are defined. In Quebec's Expert Consensus statement, the "negligible or very low" category is defined as follows:
"This category does not indicate an absence of risk. All activities in this category carry the potential of HIV transmission. The risk of transmission is associated with bodily fluid exchange (semen, pre-ejaculate, vaginal secretions, blood or breast milk). However, the small quantities of bodily fluid or virus as well as the media of exchange act to greatly limit the risk of transmission."
Of note, experts also indicated that "An undetectable viral load and the use of condoms are two effective prevention strategies that are significantly different in the way they work. No consensus currently exists on the superiority of either strategy."
The Expert Consensus adopted by the Quebec Ministry of Health is an important addition to the tools available to help frontline service providers assess and explain risk when the HIV-positive partner's viral load is undetectable. Such statements are important to ensure that clients receive accurate and consistent messaging, so that they can make informed decisions.
Hopefully this statement will lead to further discussions within frontline organizations across Canada about how best to assess and explain the HIV risk associated with an undetectable viral load.
Quebec consensus statement (French only)
Treatment and viral load: what do we know about their effect on HIV transmission? -- Prevention in Focus, Fall 2013
Certainly uncertain: Challenges in communicating HIV risk -- Prevention in Focus, Fall 2012