A mathematical model developed by the Bloomberg School of Public Health at Johns Hopkins University shows that developing effective ‘combination prevention’ programmes for men who have sex with men (MSM), including both biomedical and behavioural interventions, would significantly reduce the scale of the HIV epidemic in many countries.
In areas like Latin America, where the epidemic is mainly driven by sex between men, providing comprehensive prevention to MSM could cut overall HIV prevalence by almost 50%, a pre-conference organised by the Global forum for MSM and HIV heard.
The findings, by researcher Chris Beyrer, were presented at the Be Heard! pre-conference for MSM attended by around 700 delegates – see this report for more from the meeting.
Stephen Lewis, the former UN special envoy for HIV/AIDS in Africa, who also addressed the meeting, hailed the model as the first evidence hard enough to persuade reluctant politicians that they had to address the prevention needs of MSM in their countries.
Beyrer’s model was made possible by the increasing number of prevalence surveys of HIV in MSM from a number of countries. A literature search, combined with proactive networking with key opinion leaders, unearthed data from 138 prevalence studies of HIV in MSM from 50 different countries, covering most areas of the world with the notable exceptions of most of the Middle East and central Asia.
They reveal that, with two exceptions – Namibia and South Africa – HIV prevalence is higher in MSM than in the general population. In lower- and middle-income countries taken as a whole, MSM are 19 times more likely to have HIV than the general population, and 44 times more in developed countries.
Beyrer identified four different kinds of epidemic based on the proportions of MSM and injecting drug users (IDUs) in the population.
‘Scenario 1’ countries have epidemics mainly restricted to MSM; these are mainly in Latin America with a few outliers like Ghana.
‘Scenario 2’ comprises countries where HIV in IDUs predominated: Russia and eastern Europe. Here, recent data show that HIV prevalence in MSM is three to seven times that of the general population, though only a quarter of that in IDUs.
‘Scenario 3’ were the countries with generalised epidemics in Africa, though, even here, MSM in countries like Malawi and Kenya have two to three times the HIV prevalence of the general population.
In ‘scenario 4’ countries, most of them in Asia but including outliers like Senegal and Egypt, the one middle-eastern country with data, there is a complex mix of transmission between heterosexuals, IDUs and MSM.
Based on these data, Beyrer devised a model of the MSM epidemic in each scenario that included what could be fed in about STI prevalence, number of sex partners, condom use and – importantly – antiretroviral provision to people with HIV.
He fed in what would happen if a programme of ‘combination prevention’ including both HIV treatment and outreach and community-based behavioural programmes were made available to MSM. He then computed what would happen to the annual number of new HIV infections, not just in MSM but in the whole population, in four selected countries: Peru, Ukraine, Kenya and Thailand.
He also computed what would happen if the status quo persisted and what would happen if all current prevention support – including ARV treatment – was removed. The model lasted from 2007, on which year figures were based, to 2014.
In Peru, providing comprehensive prevention programmes for MSM would make a dramatic difference, with new cases falling from 15,000 in 2007 to 8000 in 2014, compared with an increase to 26,000 if the status quo was maintained. In Thailand the annual number of new cases, currently 33,000, would fall to 20,000.
Comprehensive prevention would make less difference in Kenya, where it would only take 3000 or so infections away from an expected 85,000 new cases in 2014, and in Ukraine, where it would only make a difference of about 1500 from an expected total of 35,500 new cases in 2014.
In Ukraine, however, there is a significant overlap between the MSM and IDU populations, and adding in comprehensive harm-reduction programmes would lead to a 40% drop in new cases to 22,000.
Beyrer ended his presentation on a very personal note, making a plea for comprehensive prevention for MSM by showing a slide of a lover who had died in 1990. “Enough with young men needlessly dying,” was his closing remark.