Improved treatment could halve HIV cases
Over half of all HIV infections among men who have sex with men (MSM) could be prevented if existing strategies were improved, new research has suggested.
According to the study, which was led by Imperial College London (ICL) in collaboration with the Stichting HIV Monitoring Foundation, more comprehensive annual HIV testing combined with rapidly treating infected men, and even treating some uninfected men (i.e. prophylactic treatment), could reduce new cases of HIV infections.
The amount of new HIV diagnoses among MSM in most areas of the developed world has not decreased significantly over the past ten years – despite free and comprehensive access to effective care and treatment.
To find out why, researchers studied the sources of new HIV infections among the MSM population in the Netherlands, where comprehensive data on almost all individuals infected with HIV is collected by the Stichting HIV Monitoring Foundation. The team analysed new infections between 1996 and 2010.
With that data, which included blood test results, the team was able to use genetic techniques to track the paths of different viruses across the population and see which individuals were likely to have infected one another. In total, 617 cases of new infections, known as transmission events, were characterised and interpreted.
Co-author of the study Professor Christophe Fraser, of ICL’s School of Public Health, said: “The last decade has seen life-changing progress in both treatment and prevention of HIV.
“Nonetheless, we find that in many populations, more needs to be done to send this epidemic into reverse. In this study, we combine analysis of the viral genetic codes and anonymised patient data to better target ramped up prevention efforts.”
The results showed that 71% of new infections were from men who did not know they were infected. Almost half of all transmissions occurred from men in their first year of infection.
Using a mathematical model to calculate how many of these cases would have been avoided if certain prevention measures were in place, the researchers found that 66% of new infections could have been prevented if three measures were implemented together: improved annual testing programmes, early start of treatment amongst diagnosed men, and uptake of antiretroviral drugs by half of all uninfected men classed as at risk of infection (i.e. pre-exposure prophylaxis, which is not currently available in Europe).
Lead author Dr Oliver Ratmann, of ICL’s School of Public Health, said: “The question we needed to answer was why new HIV diagnoses haven’t significantly reduced, despite antiretrovirals being available since 1996.
“These results, which are applicable to several other European countries, suggest that preventing new HIV infections amongst men having sex with men is challenging.
“By characterising around 600 past HIV transmission events among men having sex with men in the Netherlands, we clearly see potential for averting the majority of these through antiretrovirals, combined with new strategies leading to more comprehensive HIV testing.
“The findings of this study support making more broadly available antiretrovirals for prophylactic use by uninfected individuals in the MSM community.”
The study was supported by a grant from the Netherlands Ministry of Health, Welfare and Sport through its Centre for Infectious Disease Control – National Institute for Public Health and the Environment. Ratmann received financial support from the Wellcome Trust, while two of his co-authors received funding from the European Research Council, the Bill & Melinda Gates Foundation, Bristol-Myers Squibb, ViiV Healthcare, Gilead Sciences, Janssen Pharmaceuticals Inc., and Merck & Co.
The research has been published in the journal Science Translational Medicine.
