Gay men in Montreal using a variety of HIV prevention strategies, but little evidence of a "combination" approach to prevention being adopted

Gay and other men who have sex with men in Montreal are using a wide range of HIV prevention strategies, Canadian investigators report in AIDS and Behavior. Condoms were the main prevention method employed by HIV-negative men and the use of pre-exposure prophylaxis (PrEP) was low. The principal prevention strategy used by men with HIV was antiretroviral treatment and an undetectable viral load, or undetectable = untransmittable (U=U). Distinct groupings of prevention strategies were identified. However, there was only limited evidence that men had a “combination” approach to HIV prevention.

Over half of new HIV infections in Montreal involve gay, bisexual and other men who have sex with men. The city has adopted the goal of ending HIV/AIDS by 2030. It’s therefore essential to understand the current strategies used by gay men to protect themselves and others from HIV.

Dr Doyle and her colleagues especially wanted to see if there were distinct patterns of prevention use and if gay men were adopting a combination approach to prevention – using multiple methods such as testing, antiretrovirals, condoms and the selection of partners on the basis of HIV status, or adopting different strategies in different situations.



Choosing sexual partners of the same HIV status, or restricting condomless sex to partners of the same HIV status. As a risk reduction strategy, the drawback for HIV-negative people is that they can only be certain of their HIV status when they last took a test, whereas HIV-positive people can be confident they know their status

post-exposure prophylaxis (PEP)

A month-long course of antiretroviral medicines taken after exposure or possible exposure to HIV, to reduce the risk of acquiring HIV.


Having sex without condoms, which used to be called ‘unprotected’ or ‘unsafe’ sex. However, it is now recognised that PrEP and U=U are effective HIV prevention tools, without condoms being required. Nonethless, PrEP and U=U do not protect against other STIs. 

strategic positioning

Another term for seropositioning.

virological suppression

Halting of the function or replication of a virus. In HIV, optimal viral suppression is measured as the reduction of viral load (HIV RNA) to undetectable levels and is the goal of antiretroviral therapy.

“This assessment could aid policymakers in identifying prevention gaps and inform future responses to ensure prevention uptake is in-line with elimination needs,” write the authors.

The study population consisted of Montreal-based gay, bisexual, queer and other men who have sex with men who were recruited to the ongoing Engage prevention study between 2017 and 2018.

Participants were asked to state their HIV status. Men who were unaware were classed as HIV negative. Recruitment was open to both cis- and transgender men, all of whom were sexually active.

All participants were asked about their use of HIV prevention. For HIV-negative men, this could include recent testing, consistent condom use, use of PrEP, use of post-exposure prophylaxis (PEP), strategic positioning (being top with an anal sex partner to reduce HIV risk), serosorting (condomless anal sex with a man believed to be HIV negative) and viral load sorting (condomless anal sex with an HIV-positive man with an undetectable viral load).

For HIV-positive men, the prevention methods considered were consistent condom use, antiretroviral therapy with an undetectable viral load, strategic positioning (being bottom with a partner to reduce HIV risk), serosorting (condomless anal sex with another HIV-positive man) and PrEP-use sorting (condomless anal sex with an HIV-negative man using PrEP).

Demographic data were also obtained to see if any factors were associated with the use of a particular method of prevention.

A total of 968 HIV-negative men (including 105 who didn’t know their HIV status) were recruited to the study. Their mean age was 38 and the majority identified as male (94%) and gay (86%). Four main groupings of prevention use were identified:

  • condom use (40%),
  • low use of any kind of prevention (32%),
  • sero-adaptive behaviour including serosorting and positioning (21%), and
  • biomedical prevention including PEP and PrEP (7%).

"Dr Doyle and colleagues were concerned about the low levels of PrEP identified, especially as it’s been available in Montreal since 2013."

There was only modest evidence that men in each of these groups were using a combination of prevention techniques. Men in the condom group reported very high levels of consistent condom use (83%) and also recent HIV testing (53%), with some also reporting strategic positioning (38%). Individuals with 'low use of prevention' had 34% condom use with a third also reporting some sort of serosorting. All the men in the sero-adapative behaviour group reported serosorting or viral load sorting, two-thirds had recently tested for HIV, 45% consistently used condoms and strategic positioning was mentioned by 46%. Among men using biomedical prevention, HIV testing was universal, 83% had used PrEP and over half had ever taken PEP.

Comparison with men with 'low use of prevention' showed that several characteristics were associated with the use of a particular prevention strategy. Men who serosorted or viral load sorted were more likely to have had an HIV test. Individuals in the biomedical prevention group were more likely to have a high school diploma or higher (aOR = 2.8; 95% CI, 1.5-5.3) and an HIV-positive main partner (aOR = 3.4; 95% CI, 1,0-11.4), while also perceiving themselves to be at less risk of HIV.

Three main prevention groups were identified for men with HIV:

  • viral suppression (53%),
  • viral suppression and condoms (19%), and
  • viral suppression with seroadaptive behaviour (18%).

“With combination prevention, individuals identify the HIV prevention strategies best suited to them,” comment the authors. Dr Doyle and colleagues were, however, concerned about the low levels of PrEP identified in their research, especially as it’s been available in Montreal since 2013. The investigators therefore suggest that more is needed to increase knowledge and use this highly effective prevention method.

“Despite medication reimbursement for PrEP…out of pocket costs (up to $93/month) could be a barrier to PrEP access which should be further assessed,” the authors conclude. “Identifying sub-groups of gay men highly vulnerable to HIV transmission and tailoring appropriate combination prevention programs to their needs will also be important.”


Doyle CM et al. Combination HIV prevention strategies among Montreal gay, bisexual, and other men who have sex with men in the PrEP era: a latent class analysis. AIDS and Behavior, online ahead of print, 2020 (open access).  

doi: 10.1007/s10461-020-02965-4