The vital role of Pre-Exposure Prophylaxis in HIV prevention
Posted on the 7th November 2023
Dan Flynn discusses the importance of Pre-Exposure Prophylaxis (PrEP).
In the not-so-distant past, a human immunodeficiency virus (HIV) diagnosis was often perceived as a death sentence.
As the virus relentlessly attacked and dismantled the body's immune system, particularly the CD4 T lymphocytes essential for fending off infections, HIV's ability to hijack and manipulate these cells, facilitating its own replication, often led to the dire stage of acquired immunodeficiency syndrome (AIDS).
AIDS encompasses an array of life-threatening infections and illnesses that strike when HIV has severely compromised the patient's immune system.
A patient is considered to have AIDS when they have an AIDS-defining condition or have a CD4 cell count below 200 cells/mm3 in the blood1, leaving the host unable to fight infections.
It's critical to understand that AIDS itself is not contagious; only the HIV virus can be transmitted.
HIV enters the body via infected bodily fluids through mucous membranes, open wounds, sharing needles, or from mother to child during pregnancy, childbirth, or breastfeeding2.
Importantly, everyday interactions like kissing, hugging, shaking hands or sharing personal items like food and water do not transmit HIV3.
Fortunately, medical advancements have brought about treatments that can halt or even reverse the progression of HIV.
Antiretroviral (ARV) medications effectively thwart HIV replication and promote immune system recovery when taken as prescribed.
These medications can prevent HIV transmission, benefiting not only those living with HIV but also individuals at high risk of acquiring the virus.
ARV medicines are used to treat HIV. When taken in combination, they are effective at preventing the virus from replicating in the body, allowing the immune system to repair itself and preventing further damage when taken daily, as prescribed4.
Not only can ARVs treat HIV, but they can also prevent the transmission of HIV and can be taken by HIV-negative people who are at significant risk of acquiring the virus.
Pre-exposure prophylaxis (PrEP) medication, taken before potential HIV exposure, ensures that sufficient drug levels are present to obstruct HIV's ability to establish an infection5.
This is particularly valuable for individuals in relationships with HIV-positive partners, those engaged in high-risk behaviours, and HIV-positive pregnant or breastfeeding mothers seeking to prevent transmission to their children.
PrEP medications combine the active ingredients tenofovir and emtricitabine, which act as nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)6 and inhibit HIV's replication enzymes.
By interfering with the virus's replication machinery within T-cells, PrEP, when present in high enough concentration, prevents HIV from infecting the host by ensuring the virus cannot replicate in these cells.
Two formulations of PrEP, Truvada and Descovy, containing tenofovir and emtricitabine, are available.
Truvada, available in generic form, is widely prescribed in Europe, while Descovy, which contains Tenofovir alafenamide and is not available in generic form, is less recommended for individuals of the female sex due to limited evidence regarding its efficacy in that population.
Both tablets are intended for daily, at-home use, while a long-acting PrEP, Apretude (cabotegravir), requires administration by a healthcare professional every three months, a development approved in the United States.
When correctly adhered to, PrEP reduces the risk of HIV transmission through sex by approximately 99% and via intravenous drug use by at least 74%7.
The UK Department of Health and Social Care allocated £16 million in 2020 to provide PrEP to high-risk individuals who meet certain criteria, reaffirming its commitment to end HIV transmission by 2030 through enhanced prevention, detection, and treatment8.
This move was further backed by the Department of Health and Social Care’s commitment to end transmission of HIV in England by 2030 by better prevention, detection and treatment9.
While these prevention and treatment options are accessible in developed nations, access remains a major issue globally, especially in low- and middle-income countries with high HIV infection rates.
Most of the HIV+ population resides in low- and middle-income countries, facing difficulties accessing effective healthcare due to poverty.
In 2021, there were 20.6 million people with HIV (53%) in Eastern and Southern Africa, 5 million (13%) in West and central Africa, 6 million (15%) in Asia and the Pacific, and 2.3 million (5%) in Western and Central Europe and North America10.
Globally, Eswatini and Lesotho grapple with the world's highest infection rates, with HIV affecting nearly 27% and 21% of their populations respectively and AIDS standing as the primary cause of mortality in both nations.
Despite approximately 71% of individuals living with HIV in these countries receiving ART ART by the close of 2020, the pervasive poverty in their populations significantly impedes the accessibility of effective HIV/AIDS treatment11.
The Joint United Nations Programme on HIV and AIDS (UNAIDS) has set a pivotal goal in the fight against the HIV epidemic by 2030, aiming for a 95% diagnosis rate among people living with HIV, for 95% of those diagnosed to receive sustained ART, and for 95% of those under treatment to achieve viral load suppression12.
The 2020 Lesotho Population-based HIV Impact Assessment (LePHIA) survey paints a more optimistic future for Lesotho's battle against HIV.
It has achieved the initial UNAIDS 90-90-90 targets and aspires to meet the more ambitious 95-95-95 UNAIDS targets by 2025.
However, addressing the challenge of improving viral load suppression in young adults remains a priority, with LePHIA 2020 revealing suppression rates below 80% for adults aged 35 and under, and above 70% for those aged 25 and under.
It's worth noting that countries such as Botswana, Eswatini, Rwanda, the United Republic of Tanzania, and Zimbabwe have already attained the 95-95-95 targets, with at least 16 other nations (including eight in sub-Saharan Africa) approaching this milestone12.
The development of PrEP and effective ART has substantially reduced HIV infection rates and provided safe, efficient treatment for those living with the virus, dismantling the perception of HIV as an inevitable death sentence in recent years.
However, it's crucial to acknowledge that these advantages are primarily accessible in the developed world, whereas HIV continues to claim lives in lower-income nations.
This raises the question of whether we can claim victory over the virus if we permit it to persist unchecked in communities beyond our immediate view, which are unable to implement these measures effectively on their own. The results achieved by UNAIDS demonstrate that the mission to nearly eliminate AIDS as a public health threat by 2030 is indeed feasible if we remain committed to the path forward.
Dan Flynn is a Graduate Trainee at G&L Healthcare Advisors.
- Fast-Track - Ending the AIDS epidemic by 2030 | UNAIDS