For the first time, a study has shown that HIV treatment as prevention (TasP) works as a means of curbing new infections and suggests that Denmark in particular can likely effectively end its epidemic. Publishing their findings in The Lancet Infectious Diseases, researchers used a method known as CD4-stage Bayesian back-calculation to estimate the size of the population of Danish men who have sex with men (MSM) as well as the number of annual new infections, also known as HIV incidence, among them between 1995 and 2013.

New infections have been dropping in Denmark since the introduction of effective combination antiretroviral (ARV) treatment in 1996. Looking at the correlation between the falling HIV incidence and the increase of those on treatment for the virus, researchers found a strong connection between the two variables.

The researchers also estimated the number of MSM who had undiagnosed HIV in 2013 to be 617. At this time, the rate of new infections among Danish MSM was an estimated 1.4 per 1,000 MSM. The World Health Organization (WHO) has defined the end of the global epidemic as the point when the infection rate drops below 1 per 1,000 people.

“The Danes have done what nobody else in the world has been able to do,” Sally Blower, PhD, the study’s senior author and the director of the Center for Biomedical Modeling at the University of California, Los Angeles (UCLA), said in a press release. “They have almost eliminated their HIV epidemic, and they have achieved this simply by providing treatment.”

“Now that the number [of undiagnosed MSM] is so low, it would be fairly easy to do a social media campaign and get these men to be tested,” Laurence Palk, PhD, a coauthor of the study and a postdoctoral fellow in Blower’s lab, argued in the same release. “If they accepted treatment, it would essentially end this epidemic.”

The study authors acknowledge that the apparent success of TasP in Denmark has occurred under highly optimal circumstances, including a high level of treatment coverage thanks to the country’s national health care system and a 98 percent viral suppression rate among those on treatment. “Unless these extremely challenging conditions can be met in sub-Saharan Africa,” they write, “the WHO’s global elimination strategy is unlikely to succeed.”

To read the study abstract, click here.


To read a press release about the study, click here.