top of page

Welcome to the PrEP Impact Trial website

Illustrative picture; people watching a sunrise

PrEP is a way for people to reduce their risk of acquiring HIV.


The PrEP Impact Trial was set up to recruit 26,000 participants who are at a high risk of HIV infection in England.


 It was conducted as a prospective, open-label, single-arm, multicentre trial at 157 of 227 Sexual Health Services across England between October 2017 and July 2020.

Main Publication

Sullivan AK, Saunders J, Desai M, Cartier A, Mitchell HD, Jaffer S, Ogaz D, Chiavenna C, Charlett A, Diamente V, Golombek R, Manavi K, Priestley C, Waters LJ, Milinkovic A, McOwan A, Estcourt C, Sabin CA, Rodger A, Gold D, Gazzard BG, McCormack S, Gill ON on behalf of the Impact Study Group. 2023.

HIV pre-exposure prophylaxis and its implementation in the PrEP Impact Trial in England: a pragmatic health technology assessment.


The Lancet HIV, Volume 10, Issue 12, E790-E806, December 2023  DOI:

Message for Impact trial participants

The PrEP Impact Trial has now closed; on behalf of Chelsea and Westminster Hospital NHS Foundation Trust we would like to thank you for your participation in the trial. Your involvement has been crucial to its success.


From 1st December 2020 you will continue to be able to access PrEP, either through the new routine PrEP service or where this is not yet in place through an interim supply from your local clinic.


You can find more end of trial information here



What is PrEP?

PrEP (HIV Pre-exposure Prophylaxis) is a medicine for HIV negative people, is taken before sex, so it is pre-exposure. Prophylaxis means to prevent infection – in this case HIV. It can reduce the risk of acquiring HIV when taken as instructed. 


PrEP is made up of two drugs, Tenofovir and Emtricitabine. These drugs are known as antiretroviral medicines and have been used as part of HIV treatment for many years. You may know this medicine by its brand name, Truvada, however there are generic forms of the drug with the same active ingredients.

Who would benefit from PrEP?

You could benefit from PrEP if you are considered to be at high risk of HIV. PrEP can be used as a way to reduce your risk of HIV if you are HIV negative and don’t always use condoms. 


Other factors related to a higher risk of HIV are:

  • A recent STI (especially rectal infection such as syphilis, Hepatitis C or Lymphogranuloma venerum ) 

  • Use of PEP (post exposure prophylaxis)

  • Using some recreational drugs (crystal meth amphetamine, mephedrone or GHB/GBL) - also known as Chemsex


PrEP is not a vaccine and only provides protection from HIV so long as you continue to take it as prescribed. It is important to remember that PrEP will not protect you from acquiring other STIs. This is an important advantage of using condoms.

bottom of page