New Strategy in the Fight against HIV: Preventive Treatment for People at Risk

This post was written by Nadiya Matskiv, an internal medicine specialist at Hospital San Rafael in Madrid (Spain), and Antonio Rueda Martinez, a resident in dermatology and venerology at Hospital General Universitario Gregorio Marañon in Madrid.

A recent UNAIDS publication reveals a worrying upward trend in the rate of new HIV infections in adults since 2008

A recent UNAIDS publication (Prevention Gap report, 2016) reveals a worrying upward trend in the rate of new HIV infections in adults since 2008, underscoring the urgent need to boost preventive measures in that population.  Given the scale of the global health threat, prevention is now a crucial strategy. 

About half of all new HIV infections in Europe and North America are in men who have sex with men (MSM). Despite considerable investment, prevention initiatives have not been as effective as hoped in halting the advance of the epidemic that has been part of our lives for almost the last four decades. 

Source: Prevention Gap Report 2016

Between 2010 and 2014, the number of newly diagnosed cases of HIV infection in MSM increased by 17% in Western and Central Europe and by 8% in North America. The numbers speak for themselves.  In Spain the story is no different. The rate of new diagnoses remains above 3,500 cases per year. At the same time numbers of occult infections and late diagnoses also appear to be on the rise. 

Between 2010 and 2014, the number of newly diagnosed cases of HIV infection in MSM increased by 17% in Western and Central Europe and by 8% in North America

Initially, prophylactic treatment to prevent HIV infection was administered following exposure—horizontal or vertical—to a person who was or might be infected. In recent years, however, a new type of prophylactic treatment has been growing in importance. This new treatment is administered prior to exposure to a potential risk of infection (especially high-risk sexual practices) in groups of people considered to be particularly vulnerable. The World Health Organisation (WHO) and several other international bodies see this pre-exposure prophylaxis (PrEP) as a new strategy for preventing HIV transmission, particularly in groups at high risk of infection. The efficacy of PrEP has been demonstrated by clinical trials carried out in several countries in MSM, transsexual women, serodiscordant couples, and people who inject drugs (PWID).

HIV PrEP was first introduced in 2012 in the United States following the approval of Truvada® (a combination of emtricitabine and tenofovir disoproxil fumarate), a drug with low toxicity that has been shown to reduce the risk of HIV infection. 

The first trial to demonstrate the effectiveness of oral PrEP treatment as a strategy for preventing HIV infection was the iPrEx study, which reported a 44% reduction in the rate of new infections. Subsequently, the IPERGAY study, conducted in France and Canada, recruited MSM and transsexual women without HIV infection but at high risk. In that study, the prophylactic treatment reduced HIV risk by 86%.

A new type of prophylactic treatment has been growing in importance. This new treatment is administered prior to exposure to a potential risk of infection

While the prophylaxis is most effective when taken continuously, intermittent administration (a single dose between 2 and 24 hours prior to the risk situation followed by 2 more doses within the next 48 hours) is also yielding promising results. The importance of taking the medication as prescribed must be stressed because PrEP is only effective in patients who adhere fully to the medication regimen.

Source: Prevention Gap Report, 2016

The introduction of PrEP as a way of preventing HIV infection has also given rise to controversy for a number of reasons. These include safety concerns, concurrent increases in the rates of other sexually transmitted infections, the question of whether prophylactic treatment should be paid by public funds or by the individual, and the emergence of resistance to antiretroviral drugs. 

Today, PrEP is being used in many countries as a strategy for preventing HIV infection

Today, PrEP is being used in many countries as a strategy for preventing HIV infection in conjunction with other preventive measures, such as condoms and sex education. Its efficacy in at-risk groups is supported by evidence from numerous clinical trials. There is a proposal to introduce PrEP in Spain, but it does not appear likely that it will be implemented any time soon and the strategy does not appear to be a current priority for our health system.

In the meantime, more evidence and further research is needed on how to improve adherence to PrEP regimens, the use of PrEP during pregnancy, the emergence of resistance, long-term safety, and the potential increase in the incidence of other sexually transmitted diseases.