Researchers Present the Impact of Serosorting as an HIV Prevention Strategy

via AidsMap.com, by Gus Cairns

An meta-analysis of HIV-negative gay men’s sexual behaviour and HIV incidence rate in four HIV prevention studies, presented earlier this month at the 19th Conference on Retroviruses and Opportunistic Infections (CROI), has found that attempting to ‘serosort’ by restricting unprotected sex to partners known to be HIV negative does have efficacy as an HIV prevention strategy, when compared with using no strategy at all.

Serosorting is, however, considerably less effective in reducing the chances of acquiring HIV than four other strategies: 100% condom use, monogamy, only having insertive sex, or ‘seropositioning’ (only taking the bottom role with partners known not to have HIV and being top with partners of positive or unknown status). Interestingly, 100% condom use was the least effective of these other four strategies.

‘Seroadaptive’ behaviours include any method of attempting to reduce the risk of HIV acquisition or transmission by altering one’s sexual behaviour according to the HIV status of partners. The term ‘serosorting’ has been used in various different ways. Most commonly, it means restricting unprotected anal sex to partners known to have the same HIV status as yourself. When unprotected sex between HIV-negative men is confined to a primary relationship, with condoms used in all other encounters, this has been called ‘negotiated safety’.

 

While some studies have found serosorting in HIV-negative men to be effective, others have not. Attempted serosorting by HIV-negative people has an inherent drawback that serosorting by HIV-positive people lacks: people can only be certain of their status up to the first time they risk exposure to HIV after their last negative HIV test. Research indicates that a large minority of people in high-risk communities who assume they are HIV negative in fact have HIV, and that a large proportion of men who ‘know’ their partner’s HIV status have, in fact, tried to guess it.

 

The meta-analysis

 

Nonetheless, though serosorting is fallible, a recent meta-analysis of studies presented at CROI found that serosorting halved the likelihood of acquiring HIV compared to having no strategy at all.

The study pooled behavioural data and HIV incidence rates from four different studies in gay men:

• The HIVNET 001 Vaccine Preparedness Study (VPS), an observational study that took place in eight cities in the US between 1995 and 1997. 
• VAX 004, the first phase III efficacy trial of a candidate HIV vaccine, which took place at 61 sites in the US, Canada and the Netherlands between 1998 and 2001.
• The EXPLORE study, a randomised controlled trial of a behavioural HIV-prevention intervention that took place in six US cities between 1999 and 2003. 
• The STEP study, a phase III trial of another candidate vaccine, which took place in North and South America and Australia between 2004 and 2007.

There were a total of 12,705 HIV-negative gay men from North America included in these trials, of whom 663 (5%) acquired HIV.

Read the Rest.


[If an item is not written by an IRMA member, it should not be construed that IRMA has taken a position on the article's content, whether in support or in opposition.]

Changing HIV Risk Behaviors

Via The Forum for Collaborative HIV Research

Background: Previous studies have suggested that initial reductions in risk behavior after HIV diagnosis are not sustained. We investigated how seroadaptive tactics, including fewer total partners, serodiscordant partners, and “risk partnerships” (defined as insertive unprotected anal intercourse with an HIV– or partners unknown status), adopted by HIV+ men who have sex with men (MSM) influence HIV transmission risk over time.

Methods: MSM with acute/recent (<6 months) HIV infection were enrolled from 1998 to 2010 into the OPTIONS cohort. During 2009 to 2010, at every 3-month interval, subjects completed computer-assisted self-interviews detailing risk behavior in the prior 3 months.

To assess the relationship between transmission risk and time, we categorized individuals as being in the pre-diagnosis, post-diagnosis (as long as 6 months post-diagnosis), or later follow-up period based on their first interview. We calculated the mean number of partnerships for each category. Trends over time were assessed in subsets of individuals with data at multiple time points using linear regression.

Results: In 504 interviews, 237 MSM contributed data: 52 (10.3%) interviews assessed behavior pre-diagnosis, 65 (12.9%) post-diagnosis, and 387 (76.8%) in follow-up. The mean number of sexual partners per 3 months was significantly higher pre-diagnosis (12.2) than post-diagnosis (3.8) and follow-up (7.5) periods.

The proportion of reported partners who were HIV– or of unknown status was 0.80 pre-diagnosis, 0.24 post-diagnosis, and 0.62 in follow-up. Mean “risk partnerships” per 3 months was 2.80 pre-diagnosis, but was significantly lower in both post-diagnosis (0.09) and follow-up (0.20) groups.

Read the rest

[If an item is not written by an IRMA member, it should not be construed that IRMA has taken a position on the article's content, whether in support or in opposition.]

Prevalence of Seroadaptive Behaviors of Men Who Have Sex With Men

via U.S. Centers for Disease Control and Prevention Medical News, posted December 10, 2009

Prevalence of Seroadaptive Behaviors of Men Who Have Sex With Men, San Francisco, 2004

The researchers set out to define and measure the prevalence of HIV seroadaptive behaviors among men who have sex with men (MSM). Time-location sampling was used to recruit a community-based, cross-sectional sample of 1,211 HIV-negative and 251 HIV-positive MSM in San Francisco in 2004.

To define seroadaptive behaviors, all episodes of anal intercourse were enumerated and characterized by partner type, partner HIV serostatus, sexual position, and condom use for up to five partners in the preceding six months.

The results showed that 37.6 percent of HIV-negative MSM engaged in some form of seroadaptive behavior: pure serosorting (24.7 percent), seropositioning (5.9 percent), condom serosorting (3.9 percent), and negotiated safety (3.1 percent). Some form of seroadaptation was noted for 43.4 percent of HIV-positive men -- including pure serosorting (19.5 percent), seropositioning (14.3 percent), and condom serosorting (9.6 percent). Consistent use of condoms was reported by 37.1 percent of HIV-negative men and 20.7 percent of HIV-positive men.

"In aggregate, seroadaptive behaviors appear to be the most common HIV prevention strategy adopted by MSM in San Francisco as of 2004," the authors concluded. "Surveillance and epidemiological studies need to precisely measure seroadaptive behaviors in order to gauge and track the true level of HIV risk in populations. Rigorous prevention research is needed to assess the efficacy of seroadaptive behaviors on individuals' risk and on the epidemic."

Check out other IRMA posts on this topic:
seroadaptation, serosorting 

Do men who have sex with men use serosorting with casual partners in France?

Do men who have sex with men use serosorting with casual partners in France? Results of a nationwide survey 

Abstract:

We examined whether men who have sex with men (MSM) in France have adopted serosorting with their casual partners, serosorting being one strategy to reduce the risk of HIV transmission. We expected to see the same predictors of this practice with casual partners in France as in other similar MSM communities (HIV-seropositive, Internet dating). Data from a cross-sectional survey was used, based on a self-administered questionnaire conducted among readers of the gay press and users of gay websites in 2004. The study population consisted of MSM who reported their HIV status, as well as the practice of unprotected anal intercourse (UAI) with a casual partner at least once during the previous 12 months. Among 881 respondents included in the analysis, 195 (22%) had practiced serosorting: 14% among HIV-seropositive men and 26% among HIV-seronegative men. Serosorting was independently associated with the use of cruising venues (AOR 0.28, p=0.001) and Internet dating (AOR 2.16, p=0.051) among HIV-seropositive men, whereas it was independently associated with the use of cruising venues (AOR 0.59, p=0.013) and the fact of having less partners (AOR 1.50, p=0.046) among HIV-seronegative men. Serosorting requires an up-to-date knowledge of HIV serostatus for MSM and their UAI casual partners, and does not prevent from acquiring other sexually transmitted infections. Prevention campaigns are needed to underline the risks associated with serosorting.

Read the entire article.

Serosorting and 'strategic positioning' used by HIV-positive US gay men to reduce HIV transmission risks, shows meta-analysis

via Aidsmap, by Michael Carter

Over 40% of gay and other men who have sex with men diagnosed with HIV in the US have unprotected anal intercourse, according to the results of a meta-analysis published in the August 24^th edition of AIDS. However, there was evidence that those engaging in unprotected sex were attempting to limit the risk of HIV transmission to partners by employing strategies such as "serosorting" (sex with other HIV-positive men) or “strategic positioning” (adopting the receptive role during unprotected sex). There was no evidence that clinical factors such as adherence to HIV treatment, or an undetectable viral load affected unprotected sexual activities.

Read the rest.

Prevention for HIV serodiscordant couples: it's more than just condoms

via Aidsmap, by Michael Carter

Promoting 100% condom use may not be the most appropriate HIV prevention strategy for serodiscordant couples, according to research presented to the Fifteenth Conference of the British HIV Association. However, researchers found that there was little awareness or use of other methods of HIV prevention, such as post-exposure prophylaxis (PEP) or the impact of viral load on infectiousness.

Investigators recruited 38 serodiscordant couples (where one partner is HIV-positive, the other HIV-negative) to a prospective study lasting three years. Most (30) of the couples were gay men. To be included in the study the couples had to have been in their relationship for at least two years and to have engaged in at least 20 separate episodes of unprotected anal or vaginal sex in the previous twelve months.

The couples were interviewed about their understanding of issues such as PEP, viral load and infectiousness, and the reasons why they engaged in unprotected sex. The investigators hypothesised that there were likely to be three factors underlying unprotected sex in relationships: failure to understand the mechanisms of HIV transmission; emotional reasons; and a low concern about the consequences of HIV transmission.

Read the rest.

Increase in serodiscordant casual sex among Sydney gay men at a time when HIV diagnoses have not increased

via Aidsmap

Between 2003 and 2006, there was an increase in the numbers of HIV-negative gay men in Sydney who reported having unprotected anal intercourse with casual HIV-positive partners, report researchers in the online edition of AIDS and Behavior. However the researchers do not believe that these men form "a core group of high risk men".

Iryna Zablotska and her colleagues from the University of New South Wales analysed data from two cohort studies among Sydney gay and bisexual men: the Positive Health cohort of 760 HIV-positive men, and the Health in Men cohort of 1427 HIV-negative men. Both studies asked identical questions about sexual behaviour in annual surveys from 2003 to 2006, including questions on sex with partners of a different HIV status (rather than, as in some other studies, sex which could have been with a partner of a different HIV status).

Among the HIV-negative men, whilst the number having sex with casual partners decreased from survey to survey, there were small but statistically significant increases in the numbers having serodiscordant sex. Those having sex with casual partners they believed to be HIV positive rose from 11% to 13%, and the number specifically having unprotected anal intercourse with those men increased from 3% to 4%.

The number of HIV-positive men reporting serodiscordant casual partners did rise, but there was no statistically significant rise in unprotected anal intercourse with them.

The study examined a number of behaviours that have been previously found to be associated with sexual risk-taking, and confirmed that serodiscordant unprotected anal intercourse with casual partners was more common among men with higher numbers of sexual partners, men who met partners online or in sex clubs, Viagra users, those who injected drugs, men who used 'party' drugs regularly and those having ‘esoteric’ sexual practices (fisting, sex toys, water sports, bondage etc).

However the researchers note that men who had risky sex did not do so consistently. Over 85% of the men who reported having serodiscordant unprotected anal intercourse only reported it at one of their annual interviews, and they typically reported that behaviour with just one or two partners in the previous six months.

Read the rest on Aidsmap.

Risk reduction strategies are safer for Sydney gay men than other unprotected sex practices - but less safe than consistent condom use

via Aidsmap.

Gay men in Sydney who only have unprotected anal intercourse as part of a risk reduction strategy such as serosorting or negotiated safety have a considerably lower risk of acquiring HIV than men who have unprotected sex in other ways, report Australian researchers in the January 14^th issue of AIDS.

Men who have unprotected anal intercourse only as the insertive partner, and those who ensure that their partner withdraws before ejaculation, also had a lower risk of acquiring HIV than men who don't employ any form of risk reduction strategy when they have unprotected anal intercourse.

Taken together, men using any of these practices were three times more likely to acquire HIV than men who had no unprotected anal intercourse (UAI). However men who practiced UAI without any of these safeguards were almost eleven times more likely than men having no UAI to acquire HIV.

Moreover, withdrawal before ejaculation was the riskiest practice studied. It was associated with a five fold increase in the risk of infection (compared to no UAI).

These strategies have been used by gay men for many years and some scientists consider them to be biologically plausible, but until now there has been limited evidence on their effectiveness in the real world. One important study came in 2007 when Fengyi Jin reported that a third of Australian gay seroconverters had tried to employ a risk reduction strategy.

Read the rest.

Editorial

In an editorial accompanying the Australian report, Frits van Griensven of the Thailand Ministry of Public Health and U.S. Centers for Disease Control asked if non-condom risk-reduction behaviors can help contain the spread of HIV infection among MSM.

"In a world where condom use during anal intercourse has been the cornerstone of HIV prevention among MSM, it is remarkable that all these risk-reduction behaviors include anal intercourse without condom use, he wrote. "This inevitably raises the question why the sexual behavior identified as the primary driver of the HIV epidemic in MSM has become the central component of HIV risk-reduction behaviors employed by MSM."

"The answer lies in how institutional and individual HIV-prevention strategies have evolved over the past 25 years," he continued. In the early years of the epidemic, HIV prevention for MSM was based on the principle of "risk-elimination," such as avoidance of any unprotected anal intercourse. "Because anal intercourse appeared to be too difficult to change," he wrote, condom use soon became the norm in HIV prevention among MSM, and widespread changes in sexual behavior led to a dramatic decrease in HIV transmission among gay/bisexual men in the Western world.

HIV prevention based on risk elimination "probably worked well until the mid-1990s," van Griensven continued, at which point men started to develop "safe-sex fatigue" and began looking for alternative prevention strategies. Around the same time, younger generations of gay/bisexual men came of age who "had not personally experienced the devastating effects of AIDS in the MSM community," and the advent of HAART led many men "to no longer view HIV infection as a death sentence but as a manageable chronic disease."

With these developments, "Risk for HIV infection was no longer seen as constant across partners, but varied according to certain conditions, such as partner characteristics (e.g. serostatus) or sexual position in anal sex (e.g. insertive versus receptive intercourse)," he wrote. But, he noted, until now there have been no solid data on such risk-reduction strategies from prospective studies.

In summary, he wrote, based on the Australian data, "we can say that with the exception of withdrawal and possibly serosorting, risk-reduction behaviors in this population of MSM were equally to somewhat less effective in preventing HIV infection than was no unprotected anal intercourse."

"Serosorting and negotiated safety require honest communication between partners who are accurately informed about their HIV status, whereas the effect of strategic positioning is supported by epidemiologic data indicating the decreased risk of insertive anal intercourse compared to receptive anal intercourse," he continued. "The risk of withdrawal during unprotected receptive anal intercourse has not been well documented, but this practice seems unreliable because of possible exposure to body fluids and cells, including those from untimely withdrawal and pre-ejaculate."

Looking at the conditions under which non-condom risk-reduction behaviors can be effective, van Griensven wrote, "First of all it is crucial that MSM have updated and accurate information about their HIV serostatus…Second, HIV seropositive MSM need to be willing to disclose their HIV serostatus…Third, strategic positioning needs to be common, with HIV seronegative men taking the insertive and HIV seropositive men taking the receptive role in anal and oral sex."

He suggested that these risk-reduction behaviors may well have helped reduce HIV infection in Sydney, where HIV testing rates are high and "a strong MSM community may reduce stigma and discrimination and foster a climate of open communication and responsibility."

"These conditions will certainly be different for many other groups of MSM, such as non-urban MSM, urban MSM of lower socio-economic status, and MSM outside of the Western world," he cautioned. Thus, "we need to be careful in generalizing the results" of the Australian study to HIV prevention programs elsewhere.

1/16/09

References

F Jin, J Crawford, P Garrett, and others. Unprotected anal intercourse, risk reduction behaviours, and subsequent HIV infection in a cohort of homosexual men. AIDS 23(2): 243-252. January 14, 2009. (Abstract).

SF Morin, SB Shade, WT Steward, and others (Healthy Living Project Team). A Behavioral Intervention Reduces HIV Transmission Risk by Promoting Sustained Serosorting Practices Among HIV-Infected Men Who Have Sex With Men. Journal of Acquired Immune Deficiency Syndromes 49(5): 544-551. December 2008. (Abstract).

F van Griensven. Non-condom use risk-reduction behaviours: can they help to contain the spread of HIV infection among men who have sex with men? AIDS 23(2): 253-255. January 14, 2009.

Study examines repeated exposure to HIV in treatment-suppressed HIV patients

A new study looking at unprotected intercourse within gay couples when each partner has established HIV-infection found a correlation between anti-HIV immune response and sexual activity.

Study results showed that individuals who had regular unprotected receptive anal intercourse with partners with significant levels of HIV in their blood showed a stronger anti-HIV immune response. In addition, the magnitude of anti-HIV specific immune response correlated with their exposure to HIV through sex.

Published in the October 24th, 2008 issue of PLoS Pathogens, "Immunity to HIV-1 Is Influenced by Continued Natural Exposure to Exogenous Virus," is authored by a research team from UCSF and the Gladstone Institute for Virology and Immunology.

The researchers found no evidence of systemic superinfection (re-infection with another strain of HIV) in the receptive partners, whose virus had been successfully suppressed through antiretroviral therapy for at least five months. In a comparison group of HIV-infected couples in which both partners' viruses had been suppressed by therapy, researchers did not find the same strength of immune responses correlations or the same correlations with sexual exposure.

"We found HIV-specific immune responses in the treatment-suppressed partners that correlated with the level and route of exposure. The individuals with no detectable virus who were on antiretroviral
therapy and who were exposed to HIV through receptive intercourse with a partner with detectable virus, had the stronger anti-HIV immune responses in comparison to individuals exposed to partners whose virus was also suppressed by antiretroviral therapy, where no effect was seen," said study lead author, Christian B. Willberg, PhD, post- doctoral fellow in the UCSF Division of Experimental Medicine.

Notwithstanding the intriguing HIV specific findings, the findings also reveal an important general mechanism occurring in infectious diseases.

"We found that immune responses to chronic viral infections are influenced not only by the chronic infection existing in an individual or host, but also by exposures to exogenous virus from outside the individual or host," said study co-senior author, Douglas F. Nixon, MD, PhD, professor of medicine in the UCSF Division of Experimental Medicine.

The investigators were unable to determine from these findings whether there is any benefit from this type of repeated exposure to HIV—i.e., a type of therapeutic vaccination for HIV-infected patients with suppressed virus. Some HIV patients on antiretroviral regimens lose many of their HIV-specific immune responses over time due to the successful suppression of viral replication by therapy.

"Indeed, our hypothesis had been that in the context of these waning anti-HIV responses among the suppressed partners and the expected level of exposure from repeated unprotected receptive intercourse, we would find evidence of superinfection. While we did not find systemic super-infection, we cannot exclude limited or localized superinfections in the gut. And, antiretroviral therapy may have been the factor that prevented superinfection in these patients," said study co-senior author Robert M. Grant, MD, MPH, senior investigator at the Gladstone Institute of Virology and Immunology and associate professor of medicine at UCSF.

The study involved 49 HIV-infected gay men from the San Francisco Positive Partners Program study—a cohort of couples in which both partners are HIV-positive that began enrolling participants in 2000. Viral suppression in this study meant viral loads less than 50 copies. Among those participants whose virus had not been suppressed, the lowest viral load was 9,420 copies.

The team that designed this study benefited from its unique multidisciplinary composition. Immunologists working with social researchers were able to design a study that managed to distinguish between different levels of viral suppression and different patterns of sexual contacts and correlate the immunological aspects with the behavioral variables.

"We call the interaction between these two scientific communities together: 'social immunology'. It may be true that patterns of social activities shape immune responses generally, as we observed for people with HIV having contact with other HIV infected persons. Obviously more study is needed and we would like to see whether social immunology will continue to offer important insights," said Grant.

"While we have not found a case of superinfection in our cohort of chronically infected HIV couples, a handful of cases of superinfection verified by linkage to a known partner's virus have been reported in chronically infected HIV patients. It is also important to stress, these findings do not address the negative consequences of acquiring other sexually transmitted diseases through engaging in unprotected sex or the potentially positive consequences that unprotected sex may have in partnerships where both individuals are HIV-positive," said study co-author, J. Jeff McConnell, MA, director of the Positive Partners study at the Gladstone Institute for Virology and Immunology.

Read the paper here.