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
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
‘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
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