Viral load and safer sex: community use and awareness

Once HIV status is disclosed, another factor can be considered by people attempting to minimise their HIV risk. Some studies have found that gay men are questioning each other about their HIV viral load in order to try and establish if they are infectious.

Interestingly, early studies tended to present this as a problem: the thing that interested the researchers was whether a belief that having an undetectable viral load made one less infectious was associated with having unprotected sex.

Often it was. For instance, a study of 533 gay men from San Francisco presented at the Barcelona International AIDS Conference in 2002¹ found that 53% of the HIV-negative gay men and 43% of the HIV-positives believed that the likelihood of transmitting HIV was reduced if a man with HIV had an undetectable viral load. Both positive and negative men who believed that an undetectable viral load made a person with HIV less infectious were more likely to engage in what was called ‘high risk’ sexual behaviour. One in five HIV-negative men reported requesting information about their partner's viral load before deciding whether to have unprotected receptive anal sex.

Similarly, a meta-analysis of 25 studies (all conducted between 1996 and 2001, and mostly with US gay men) found that taking ARVs was not associated with ‘sexual risk taking’, but believing that they made people with HIV less infectious was.²

The investigators wished to answer three questions:

• Are HIV-positive individuals taking HAART more likely than HIV-positive patients not taking anti-HIV therapy to have more unprotected sex?
• Are HIV-positive individuals who are aware that they have an undetectable viral load more likely than HIV-positive patients who know that they have a detectable viral load to have unprotected sex?
• Are HIV-positive or HIV-negative individuals who believe that HAART or an undetectable viral load reduces the risks of HIV transmission more likely to have unprotected sex?

There was no relationship found between taking ARVs and unprotected sex, rather the reverse: the median reported incidence of unprotected sex was 33% in people taking treatment and 44% amongst patients not receiving it. Similarly, the prevalence of unprotected sex was a median of 39% for the patients with an undetectable viral load and a median of 42% for individuals with a detectable viral load.

However, the likelihood of unprotected sex was significantly higher in people who believed that HAART reduced the risk of HIV transmission. The median reported incidence of unprotected sex was 49% amongst individuals who believed HAART or a low viral load reduced the HIV transmission risk and a median of 38% for individuals who did not share this belief.

In a 2005 study from San Francisco,³ 78% of 507 gay men questioned were familiar with the term ‘viral load’ and one third (111 of the total sample) had discussed viral load with a partner of a different HIV status during the previous year in order to make decisions about which sexual practices to engage in.

Of those who had discussed viral load, more than half estimated that they used viral load disclosure to guide sexual decision-making in at least 70% of their sexual encounters.

In a study from Sydney reported at the same conference⁴ researchers asked 119 men who were in a serodiscordant regular relationship about whether they used viral load as a basis for their decisions on condom use. Nearly twice as many (39%) reported unprotected anal intercourse when the partner’s last viral load test was undetectable as when it was detectable (21%).

In contrast, researchers conducting a qualitative study with HIV-positive gay men in the UK were surprised to find that their respondents did not consider viral load when making their sexual choices. During in-depth interviews exploring sexual risk with 42 men who reported having unprotected anal intercourse, no one reported attending to their viral load in relation to their risk of transmission.⁵