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HIV Trends in San Francisco and London: An AIDS 2014 Q&A

, by San Francisco AIDS Foundation

At AIDS 2014, underway this week in Melbourne, Australia, thousands of researchers, advocates, policymakers, and community members are gathered to learn the latest in HIV science and policy—and, importantly, to share knowledge across borders, with the goal of “stepping up” the HIV/AIDS response.

To this end, on July 24 researchers presented findings from a comparison of HIV trends in two major cities: San Francisco and London. The team, hailing from community-based organizations, government agencies, universities, and public health departments, assessed how differences in HIV testing rates, risk behavior, and antiretroviral treatment coverage may be contributing to divergent HIV prevalence and incidence trends among gay and bisexual men and other men who have sex with men (MSM). (Read the study abstract here.)

The first AIDS cases appeared in San Francisco and London at roughly the same time and the two cities have similar numbers of gay and bi men living with HIV—but there are some significant differences. For example, London has a much higher proportion of gay and bisexual men living with HIV who don’t know it: Since 2006, an estimated 20% to 25% of HIV infections in this population in London have remained undiagnosed, whereas undiagnosed HIV infections among gay and bi men in San Francisco dropped from 21.7% to 7.5% in the same time period. Why?

Jen Hecht

Jen Hecht

Study co-author Jen Hecht, MPH, director of program development and operations at San Francisco AIDS Foundation, spoke with BETA about the study findings, what they mean for HIV prevention efforts moving forward, and what she and her colleagues hope to accomplish by sharing their data with the AIDS 2014 community.

What did you and your fellow researchers determine are the key factors contributing to divergent HIV incidence and prevalence trends in the London and San Francisco?

We found the most important factors are testing frequency among MSM in San Francisco, along with greater opportunity for positive-positive serosorting [choosing to have sex only with partners believed to share your HIV status] due to greater likelihood of disclosure and greater ease of finding partners of the same status, and also slightly greater risk-taking behavior—higher rates of condomless anal sex—among MSM in London.

Sexually transmitted infection rates in London suggest higher rates of serodiscordant [mixed HIV status] sex in London. Importantly, for HIV-negative men in London, serosorting wouldn’t confer as much protection as in San Francisco, since the percentage of people with undiagnosed HIV is higher in London and therefore the likelihood that a negative person would inadvertently partner with an unknown HIV-positive individual is higher.

Given that antiretroviral treatment has a protective benefit as well, earlier treatment in San Francisco may also be a factor affecting lower transmissibility. Also, during the session question-and-answer period, one audience member from London pointed out that Londoners haven’t yet been able to agree on a plan for HIV prevention, while San Francisco has one city-wide plan and San Francisco Department of Public Health has focused funding accordingly; this may also contribute to differences.

Moving forward, do these findings suggest ways to better focus our HIV prevention efforts in cities with stubborn HIV infection rates among gay and bi men?

In San Francisco, the data point to a need for better retention in HIV care (and also increased access to care and reduced barriers to care), which is likely a result of a poorer and more “patchwork” health care system than in the U.K. (The Affordable Care Act may mitigate this over time.)

In London, the data point to a need for outreach, messaging, and gay health centers that may increase HIV testing and frequency of testing among gay and bi men. The data also point to the importance of educating men about the imperfect strategy of negative-negative serosorting.

What do you and your colleagues most hope to accomplish by presenting these data at AIDS 2014? 

Of course, the HIV response needs to be tailored to cities based on where their weaknesses are in addressing HIV prevention needs (such as San Francisco needing to focus on retention in care and viral suppression, and London focusing on testing). That said, comparing these epidemics allows us to look at trends in different cities, as well as best practices for HIV prevention in two cities with some similar characteristics. I think many people look to San Francisco to see what we’re doing in our HIV response—and the success that we’re having—so they can replicate it in their home settings.

The presentation opened a dialogue across nations regarding epidemiologic trends, HIV prevention responses, and what works. In fact, out presentation received more comments than any other in this session. The comments showed that people were considering the potential importance of gay health centers and culturally sensitive services as interventions to address MSM epidemics.

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See all of BETA’s coverage of AIDS 2014, and stay tuned for more news and views from this major international conference.

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