Gay men using viral load info to decide when to use condoms or avoid sex acts, say 2 US studies

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A large proportion of gay men surveyed in San Francisco and Boston are using viral load test results to make decisions about sexual practices and the transmission risk of particular sex acts, according to findings presented this week at the United States National HIV Prevention Conference in Atlanta.

Although an undetectable viral load indicates that levels of HIV in the blood are very low and that transmission is less likely, viral load can change rapidly due to treatment failure. Research has also shown that men with undetectable viral load in blood may nevertheless have potentially infectious levels of HIV in their semen due to the presence of infections such as gonorrhoea or urethritis. Detectable levels of HIV have also been discovered in the rectal secretions of HIV-positive men even when they have undetectable HIV levels in their blood.

Two research groups set out to determine how gay men in San Francisco and Boston are using information about viral load to make decisions about unprotected sex.

San Francisco – one in five say decisions on sexual activity have been guided by viral load in last year

In the first study, San Francisco Department of Public Health and the US Centers for Disease Control and Prevention questioned 507 men who have sex with men (MSM) recruited from social venues, street locations and community agencies.



Receptive anal intercourse refers to the act of being penetrated during anal intercourse. The receptive partner is the ‘bottom’.


Refers to the mouth, for example a medicine taken by mouth.


Insertive anal intercourse refers to the act of penetration during anal intercourse. The insertive partner is the ‘top’. 


The presence or absence of detectable antibodies against an infectious agent, such as HIV, in the blood. Often used as a synonym for HIV status: seronegative or seropositive.


In HIV, refers to the act of telling another person that you have HIV. Many people find this term stigmatising as it suggests information which is normally kept secret. The terms ‘telling’ or ‘sharing’ are more neutral.

Seventy-eight per cent of those 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.

Among study participants, HIV-positive individuals were more likely than HIV-negative men to use viral load information to make sexual decisions, and African Americans were more likely than whites to base sexual risk behavior on such information. Significantly, among HIV-negative men with serodiscordant partners, those who discussed viral load reported a greater willingness to engage in unprotected sex with a partner whose viral load was undetectable.

Study authors note that while they surveyed a limited number of men in a single metropolitan area, these findings suggest that many MSM are using viral load disclosure to make sexual risk decisions, contrary to guidance from public health officials. Researchers recommend that HIV prevention programmes targeting gay and bisexual men underscore the limitations of using viral load as an individual indicator of infectivity.

Boston – many HIV-positive men modifying sexual practices to avoid infecting partners

In an effort to reduce the risk of infecting partners, many HIV-positive gay and bisexual men may be adopting new sexual practices they believe will lower chances of HIV transmission, according to a new study by Boston’s Fenway Community Health Center.

Hilary Goldhammer and colleagues found that a significant proportion of HIV-positive MSM are opting to engage in oral rather than anal intercourse. And among those who do have anal sex, many HIV-positive MSM are choosing to be the receptive rather than the insertive partner.

Fenway surveyed 104 HIV-positive MSM clients about their sexual behaviors. The cohort was predominately white (77%), well-educated (83% had either completed college or had some college education), and in their 30s and 40s (median age 42). Forty percent of participants said they try to reduce the risk of transmission by having oral instead of anal sex with HIV-negative partners. One-third (33%) reported more frequently choosing the receptive position during anal intercourse since becoming HIV-infected, and a similar proportion (34%) said they do not engage as the insertive partner during anal intercourse with an HIV-negative man, due to concerns about transmitting HIV. Thirteen percent reported that they only have sex with HIV-positive partners. A majority (56%) said they disclose their own serostatus to partners before sex, while 32 percent ask their partners to disclose.

The researchers report that 10 percent of participating MSM believed that they could not transmit HIV if they were the receptive partner during anal sex. Nearly two out of three (64%) of the men believed their viral load affected their likelihood of transmitting, and 3 percent believed transmission was not possible with an undetectable viral load. This belief was associated with a greater willingness to have unprotected sex, although the study did not ask participants about their actual condom use during sex.

The researchers believe their findings suggest that many HIV-positive MSM – in the absence of guidance or endorsement of public health agencies or community educators – are using information about viral load and partner serostatus, and adopting different sexual practices, in an effort to protect their partners from possible infection.

Researchers recommend that this wide range of beliefs and practices be considered in the development of prevention programmes for HIV-positive MSM in a similar way to campaigns already targeted at gay men in the United Kingdom(click here for an example of a campaign developed by Gay Men Fighting AIDS) and Australia.

According to the study authors, it is also critical that MSM recognise that these practices are by no means risk-free. While public health officials believe that reduced viral load is likely to lower a person’s risk of transmitting HIV, transmission can occur even when viral load is undetectable. Similarly, while oral and receptive anal sex may present a lower risk for transmission of HIV from positive persons to their uninfected partners, HIV can and has been transmitted through these practices.


Goldhammer H et al. Beliefs about viral load, sexual positioning and transmission risk among HIV+ men who have sex with men (MSM): Shaping a secondary prevention intervention. 2005 National HIV Prevention Conference, Atlanta, USA, presentation W0-D1201.

Guzman R et al. Communication of HIV viral load to make sexual risk decisions with serodiscordant partners among a diverse sample of men who have sex with men. 2005 National HIV Prevention Conference, Atlanta, USA, presentation TP-113.