According to the Joint United Nations Programme on HIV/AIDS (UNAIDS), an estimated 5,000 new cases of the human immunodeficiency virus (HIV) occur every day across the globe.
Finding feasible healthcare solutions to the HIV/AIDS epidemic has been a global priority, and according to a 2017 report from UNAIDS, preventative efforts have been successful in reducing the number of new HIV infections by almost 50% since the peak of the epidemic in 1996. Moreover, while current pharmaceutical therapies for HIV and Acquired Immunodeficiency Syndrome (AIDS) treatment have gotten better at halting transmission of the virus and mitigating progression of the disease, treatment options can be prohibitively expensive, and a cure remains elusive, given the mechanism of the viral infection.
HIV is a retrovirus that copies its genome into that of a human host’s cells, and then hijacks the host cell’s replication machinery, allowing the virus to replicate. HIV is particularly problematic because the cells it targets are immune cells. The specific cells targeted are CD4 cells, a type of T cell that is normally responsible for aiding in the immune system’s attack against foreign infections. Therefore, HIV infections leave the immune system in a vulnerable state, making HIV-positive individuals more likely contract opportunistic infections, such as toxoplasmosis, cryptococcal meningitis, and some cancers. Contracting an opportunistic infection can lead to an AIDS diagnosis, given that the CD4 cell count falls below a specific threshold.
Treatment for HIV/AIDS often involves a drug cocktail of several medications used to limit progression of symptoms. One of these medications, known by its brand name Truvada, is actually a combination of several drugs: disoproxil, emtricitabine, and tenofivir, each of which is designed to treat infection by slowing progression of the disease. Specifically, Truvada works by inhibiting the enzyme reverse transcriptase, which is essential for HIV to replicate. In addition to being used in treatment after infection, Truvada is also being explored as preventative therapy for HIV-negative people.
In 2012, the Food and Drug Administration approved Truvada as a preventative therapy for HIV-negative people, making it the first drug to be approved for this use. Truvada is taken in pill form, and recent studies have investigated its efficacy as a preventative medication through a treatment technique known as pre-exposure prophylaxis (PrEP).
PrEP is a treatment designed for individuals who are HIV-negative, but at high risk for HIV transmission, to lessen their chances of HIV infection through daily administration of the pill. PrEP attempts to mitigate an individual’s chances of HIV infection by preventing the virus from permanently establishing itself. This is a considerable measure, given that once HIV infection occurs, even though modern treatment can effectively manage symptoms and slow progression of the disease, it is impossible to fully eradicate the virus from the body. Therefore, PrEP aims to prevent the virus’ initial establishment of permanent infection. However, for PrEP to be effective, it is imperative that the Truvada pill is taken daily and coupled with other preventative methods such as usage of condoms.
In addition, it would be false to consider PrEP a vaccination for HIV. A vaccination prevents infection by introducing an individual’s cells to weakened or dead versions of a pathogen to train the immune system and allow development of antibodies to fight the infection. Conversely, PrEP operates under the idea that if a high risk HIV-negative individual has enough of the antiviral medications already present in his or her body, the risk of infection is drastically reduced and disease transmission can be prevented.
Funding for use of PrEP as a preventative measure for HIV/AIDS has been approached with hesitance by policymakers who are unsure of its efficacy at the population level. However, a new study on HIV infection transmission in gay and bisexual men in New South Wales, the most populous state in Australia, serves as the first-of-its-kind population study investigating the success of Truvada in PrEP.
The study, published in mid-October of this year in the medical journal The Lancet HIV, found significantly rapid declines in the number of HIV diagnoses in the target population, and has attributed these declines to PrEP implementation. In the year prior to the study’s beginning, 149 new infections were recorded among the recruited high-risk population of gay and bisexual men in New South Wales. In the first year after the study began and PrEP was implemented, this number dropped to only 102 new infections. The study sheds light on the population-level benefits of PrEP and may serve as impetus for policymakers to consider funding the treatment for targeted preventative therapy for high-risk, HIV-negative individuals.