Show me the Evidence

Guest Editorial on HIV Prevention

Dr. Marc Ouellette, Scientific Director, CIHR Institute of Infection and Immunity

When third-year University of Swaziland engineering student Senzo Simelane gingerly walked away from a clinic in Swaziland, he said, “At the end of the day, it is quite worth it. HIV infection versus two weeks of pain – the pain is probably worth it.”

Simelane was one of the more than 600,000 men in southern and eastern Africa to undergo circumcision as part of HIV prevention efforts. The research findings of Dr. Stephen Moses of the University of Manitoba showed a 60% reduction in the risk of acquiring an HIV infection in circumcised men, leading the World Health Organization and UNAIDS to advocate strongly for male circumcision programs in 14 countries.

Circumcision is indeed a valuable tool in the fight against the transmission of the virus. But it is just one piece in a combination prevention toolkit that includes condom use, testing, treatment, abstinence and education. Without an HIV vaccine, which remains elusive, true eradication is unlikely in the near future. For now, a combination of prevention interventions is required to mount a successful long-term, comprehensive response against the disease.

One such preventive intervention is ART (antiretroviral therapy). The advent of antiretroviral drugs has had a profound effect on the life expectancy of people who are HIV positive. ART has prevented the progression to AIDS and death for millions and has transformed HIV infection into a manageable chronic condition. These drugs are prescribed to infected individuals at the point in their disease progression where the amount of virus in the blood (or viral load) becomes too high.

Antiretroviral drugs slow the rate at which HIV multiplies in the body, allowing the immune system to stay healthy, delaying progression of the disease and dramatically preventing morbidity and mortality. In other words, antiretroviral therapy keeps the amount of HIV virus in the body low. The lower the viral load in the blood, the less likely the chance for transmission. This understanding has been used in new treatment modalities, including the prevention of mother-to-child transmission (PMTCT) and in preventing transmission in serodiscordant couples, as well as in sexual and injection drug use settings.

The HIV Prevention Trials Network study HPTN 052, which was funded by the National Institutes of Health, showed that treating HIV-infected individuals with ART can reduce the risk of sexual transmission to their uninfected partners.

Other applications for antiretroviral drugs include short-term use of antiretroviral treatments to reduce the likelihood of HIV infection after potential exposure. Post-exposure prophylaxis (PEP) is used with uninfected individuals following exposure at work (such as unintentional needle pricks), or during sexual intercourse. Similarly, pre-exposure prophylaxis (PrEP) is a prevention treatment in which HIV-negative individuals deemed to be involved in high-risk activities take antiretroviral medication daily to try to lower their chances of becoming infected with HIV if they are exposed to it.

In studies, PrEP has been shown to be effective in men who have sex with men and heterosexual men and women. In November 2010, the National Institutes of Health announced the results of a large, multi-country research study looking at the role of PrEP in HIV transmission. The study found that men who have sex with men and who used an antiretroviral drug daily, while at the same time combining this treatment with a comprehensive package of prevention services including regular monthly HIV testing, condom provision, and management of other sexually transmitted infections, showed an average of 44% additional protection. The drug used in the study was recently approved in the U.S. as the first prescription drug to prevent HIV among those at risk for the infection.

Researchers are approaching HIV from as many angles as possible to try to make a dent in the global number of infected individuals. Circumcision, ART, PEP, PrEP, PMTCT, testing, education and awareness are all valuable tools for prevention of HIV infection. The long road to eradication includes these and other solutions yet to be discovered in the common goal of a world without AIDS.