Does viral load testing shorten the window period for diagnosing HIV?

  • Research type

    Research Study

  • Full title

    Does qualitative viral load testing shorten the window period for diagnosing HIV?



  • Contact name

    Gary Whitlock

  • Contact email

  • Sponsor organisation

    Chelsea & Westminster Hospital NHS Foundation Trust

  • Duration of Study in the UK

    1 years, 0 months, 0 days

  • Research summary

    The HIV test we use in sexual health clinics (called the 4th generation test) can diagnose HIV around 2 weeks after someone has come into contact with the virus. However, this test can be negative within the first 2 weeks of infection. This may lead to people being told they do not have HIV when in fact they do. This means that they are at very high risk of transmitting HIV to someone else without knowing it.
    A newer test looks for the HIV virus itself (called the viral load assay). This allows HIV to be detected about a week earlier than the test described above. However, this test is expensive and takes several days for a result to come back.
    At our clinic we diagnose over 1 in 6 of all new HIV infections in the UK. In fact, we see a lot of men-who-have-sex-with-men (MSM) who are at the highest risk of acquiring HIV, in particular those who come for HIV post-exposure prophylaxis (PEP) or who are taking, or might be about to take, pre-exposure prophylaxis (PrEP).

    We would like to ask MSM who come to our clinic for PEP or who say they are about to start PrEP to have a further test (called the Cepheid GeneXpert qualitative HIV viral load test) as well as the standard one. After we’ve done both tests on 600 people, we’ll look to see how the new test does against the existing one at picking up undiagnosed HIV infections.

  • REC name

    London - Fulham Research Ethics Committee

  • REC reference


  • Date of REC Opinion

    25 Jul 2016

  • REC opinion

    Favourable Opinion