World AIDS Day takes place on 1 December each year. Its goals are to unite people worldwide in the fight against HIV, support those living with the virus, and pay tribute to those who have passed away due to AIDS-related illness.1

Approximately 89,000 people in the UK are living with HIV, with a global estimate of 36.7 million in 2015.2,3 Despite recent medical advances in treatment, there is still a lack of awareness regarding HIV prevention options, as well as stigma and discrimination surrounding HIV and AIDS.4

World AIDS Day is important in reminding us that HIV is not a thing of the past – there is still a need to raise awareness, improve education and tackle prejudice.

Pre-exposure prophylaxis (PrEP) – what is it?

In short, PrEP is the pre-emptive use of drugs to prevent disease in those not yet exposed to the disease-causing agent.

The term is notably used to describe the use of antiviral drugs as a method of HIV prevention in HIV-negative individuals. HIV PrEP consists of the combination drug tenofovir/emtricitabine (licensed under the brand name Truvada®). These drugs work by preventing reverse transcription within HIV-infected human cells. HIV is a retrovirus and replicates by using the host cells’ own intracellular machinery to integrate its genetic material into the host genome. In other words, HIV genetically modifies the cells of its human host – a process almost impossible to reverse (although there are scientists working on this, and removal of HIV DNA has been achieved in vitro5). For this reason, HIV infection is a chronic condition, whereas infections by non-retroviruses such as adenovirus, measles virus, influenza virus, etc. can ultimately be cleared by the immune system. While PrEP does not offer complete protection from HIV, clinical studies have found it to be more than 90% effective when taken as prescribed.

In comparison, post-exposure prophylaxis (PEP) is an approach to HIV prevention in individuals already exposed to the virus. PEP must be started within 72 hours of exposure to HIV, and consists of a number of antiretroviral drugs at high doses. PEP is less effective than PrEP, preventing up to 80% of HIV infections.

Until a cure for HIV infection is developed, treating physicians are limited to managing infection using highly active antiretroviral therapy (HAART). HAART is expensive and relies on HIV-positive individuals taking combinations (or “cocktails”) of antiviral drugs regularly for the rest of their lives. Failure to adhere to the strict dosing regimen can lead to the virus becoming resistant to one or more of the drugs. This will eventually increase their viral load, increasing their risk of infecting others, and ultimately mean these individuals go on to develop acquired immune deficiency syndrome (AIDS).

Access to PrEP in the UK

PrEP has been proven to be highly effective in preventing HIV infection in high-risk individuals. However, it can be expensive and the cost-effectiveness of its provision under universal healthcare systems is currently under debate.

Cost-effectiveness is a type of economic analysis that quantifies benefit using outcome measures that reflect mortality or quality of life (QoL).6 It is a tool commonly used to inform or rationalize budget allocation within the healthcare sector. A recent modelling study and health economic evaluation published in The Lancet Infectious Diseases suggested an introduction of a PrEP programme is both cost-effective and cost-saving in the long term.7 The study found that such a programme would result in a cost saving of £1 billion and prevent 1 in 4 cases of HIV infection over an 80-year time period. Moreover, PrEP would be cost-effective in relatively less time when considering the patent expiry of drugs and consequent availability of cheaper generics. For example, the patent for tenofovir expires in 2017-18, and if the cost of PrEP reduces by 80% from 2019, cost-effectiveness could be achieved in just 20 years.8

While Scotland offers full PrEP provision on its NHS, it is currently the only part of the UK to do so. England does not currently offer PrEP, while Wales offers PrEP as part of an initial 3-year programme.9 NHS England have challenged the funding of PrEP, seeking further evidence of the cost versus benefit. It also argues that funding should be the responsibility of prevention-related services of local authorities. 10 However, following judicial review and subsequent defeat, NHS England announced it will conduct the PrEP IMPACT trial, and this began in September 2017.11,12 The trial aims to address important questions that will determine the future implementation of PrEP on a large-scale. These questions are related to PrEP eligibility and uptake, the duration of treatment, and its impact on the incidence of HIV and STIs in the population. The PrEP IMPACT trial will provide PrEP to 10,000 participants in selected sexual health clinics and run for up to 3 years.


It has been reported by some parts of the UK media that PrEP is a ‘lifestyle drug’, and it has even been referred to as a ‘promiscuity pill’ that would encourage high-risk sexual activity. Spending public funding on PrEP has been seen by some as diverting limited resources in the NHS from other sensitive areas such as funding for new cancer treatments. However, this is at odds with the recent evidence suggesting the introduction of a PrEP programme will save the NHS money in the long term. Funding decisions in the NHS should be made based on the best available evidence about efficacy and cost-effectiveness, and not on moral judgements of individuals. While the effectiveness of PrEP is proven, and there is already much evidence to suggest that it is cost-effective, the NHS is waiting for the results of the PrEP IMPACT trial before deciding whether to overturn their controversial decision not to fund PrEP for all high-risk individuals in England, a decision that could be 3+ years away.

The UK has recently witnessed a substantial decline in HIV infection rates, particularly among gay and bisexual men.13 This is thought to be driven by an increase in HIV testing and improved uptake of antiviral therapy following diagnosis. Sustained condom use with casual partners and internet-purchased PrEP are also believed to be contributing factors. Widespread access to PrEP through the NHS in England could play a vital role in further strengthening the UK’s current HIV prevention strategy.


  1. World AIDS Day. 2017. Available from: Accessed 27 November 2017.
  2. National AIDS Trust. UK HIV Statistics. 2017. Available from: Accessed 27 November 2017.
  3. UNAIDS. Fact sheet - Latest statistics on the status of the AIDS epidemic. 2017. Available from: Accessed 27 November 2017.
  4. AVERT. HIV Stigma and Discrimination. 2017. Available from: Accessed 27 November 2017.
  5. Hu W, Kaminski R, Yang F, et al. RNA-directed gene editing specifically eradicates latent and prevents new HIV-1 infection. PNAS. 2014;111:11461–66.
  6. Dawson GF. Chapter 20 – Economic analysis. Easy interpretation of biostatistics. 2008; 159–62.
  7. Cambiano V, Miners A, Dunn D, et al. Cost-effectiveness of pre-exposure prophylaxis for HIV prevention in men who have sex with men in the UK: a modelling study and health economic evaluation. Lancet Infect Dis. 2017. doi: 10.1016/S1473-3099(17)30540-6.
  8. UCL News. National roll-out of PrEP HIV prevention drug would be cost-effective. 2017. Available from: Accessed 27 November 2017.
  9. i-base. Introduction and access to PrEP in the UK. 2017. Available from: http://i Accessed 27 November 2017.
  10. BBC News. HIV 'game-changer' to arrive next month. 2017. Available from: Accessed 27 November 2017.
  11. The PrEP Impact Trial. 2017. Available from: Accessed 27 November 2017.
  12. BBC News. NHS watchdog to cost up HIV Prep drug. 2017. Available from: Accessed 27 November 2017.
  13. Public Health England. HIV in the United Kingdom: decline in new HIV diagnoses in gay and bisexual men in London, 2017 report. 2017. Available from: Accessed 27 November 2017.