Welcome to the PrEP Impact Trial website

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. 

Recruitment to the trial ended on 12th July 2020 and participants will have their final trial visits up until 12th October 2020.

At the final visit, if participants need PrEP, they will be able to access it either through the routine service (if established) of if not, via an Interim Supply being provided by NHS England


If you need PrEP and are not on the trial, please ask your clinic if they have PrEP available through the new commissioned service.

For other alternative ways to access PrEP in the UK see http://i-base.info/guides/prep/introduction-and-access.

End of Trial - PrEP Supply

A fully commissioned PrEP programme has been agreed for England.

Due to the current COVID-19 situation it may be that the programme will not be fully operational at the same time in all clinics across England by the end of the trial. Therefore, an ‘interim’ supply is available for Impact participants with on-going PrEP need, who cannot immediately access PrEP via the commissioned programme. The Interim supply is provided by NHS England.


If you need PrEP you will be able to access PrEP through either

  • the National Programme

  • or Interim Supply from your local clinic.


Participants can find out more about the End of Trial Process here.


On behalf of Chelsea and Westminster Hospital NHS Foundation Trust

we would like to thank you for your on-going participation in the PrEP Impact Trial.



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.

© 2017 PrEP Impact Trial