HIV Testing - Which Test Is Right For Me?

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Medically reviewed by: Dr Nicholas Antonakopoulos

Last reviewed: 19 Mar 2019

Contents of this article

Whether you think you might have contracted HIV, or just want to rule it out completely, there are a number of different tests out there that can hopefully put your mind at ease.

All tests have different window periods, (that’s the length of time HIV needs to be in your body for, before it will start to show up on a test), so it’s important you find the one that’s right for you:

If you've put yourself at risk within the last week, you'll need a test with a smaller window period. But if your risk was 6 months ago or more, it doesn't really matter so much. Zava offers an HIV test kit with a one month window period.

We can help you decide on the most suitable test to take but, with a quarter of all UK HIV suffers currently living undiagnosed, if there's even the slightest chance you might have HIV, it's essential you get yourself tested.

Which test options are there?

Q. I might have caught HIV this weekend.

A. If you think you may have contracted HIV within the past 72 hours, unfortunately, there's no way of knowing for sure as no HIV tests currently operate within this time frame. But you are advised to take emergency PEP treatment anyway.

Q. I might have caught HIV this month.

A. Testing options: HIV RNA PCR test

Works from: at least 7-10 days after unprotected sex

Available from: private clinics

Accuracy: 99.89% accurate for HIV 1&2

If there’s a chance you may have caught HIV in the last couple of weeks and you want to know for sure, you can request a PCR RNA test at certain clinics. They are more expensive and complicated than regular tests so aren’t offered by all clinics. Those that do may charge up to £250 (including consultation fee).

RNA tests detect the genetic material (DNA) that makes up the HIV virus. You don’t need to wait for any antigen or antibody build up so it can potentially detect an infection earlier.

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Q. I may have caught HIV this year / I just want to make sure

A. If you’re just going for a routine HIV check-up, you will be offered one of the following two tests:

1. Antibody (Ab) test

Works from: at least 3 months after unprotected sex

Available from: GP, GUM clinics, online

Accuracy: 99.97 % accurate for HIV 1&2

Rather than identifying the HIV virus itself, these tests look for specific proteins (antibodies) that are produced by your body in response to the infection. They’re highly accurate, but as you need to wait for an appreciable number of antibodies to build up, they’re not really suitable for those who’ve put themselves at recent risk.

2. Fourth Generation (HIV 1&2 Abs/p24 Ag) test

Works from: At least 4-6 weeks after unprotected sex

Available from: GP, GUM clinics, online

Accuracy: 99.8% accurate for HIV 1&2

This is the standard test offered by most UK clinics, as recommended by the British Association of Sexual Health and HIV (BASHH). It detects HIV-fighting antibodies produced by your body (like the Ab test does) but also the specific p24 antigens found on the surface of the HIV virus itself. These antigens are detectable in your body earlier than the antibodies are, so they can give an accurate result after a shorter window period.

Q. I don’t like needles, (and may have caught HIV at least 3 months ago) what can I do?

A. Testing options: Antibody (Ab) oral fluid test

Works from: at least 3 months after unprotected sex (maybe more)

Available from: certain GUM clinics, online

Accuracy: 98% accurate for HIV 1&2

If you don’t like injections or needles, you can request an antibody (Ab) test that uses a fluid, ‘oral mucosal transudate’ from your cheek and gums instead of blood. Again, the test carries a window period of 3 months which means that if you’ve put yourself at risk during this time, you’ll need to take another test in a few months’ time.

Q. I may have caught HIV 3 months ago, and I want my test results immediately.

A. Testing options: Rapid HIV (antibody test)

Works from: 3 months after unprotected sex

Available from: some GUM/ HIV clinics

Accuracy: 98- 99 % accurate for HIV 1&2

Some clinics in the UK offer rapid HIV testing which gives you a result in under an hour. This means you can take the test and get your result in the same visit. The test is an antibody (Ab) test and can be done via blood sample or oral swab.

Rapid HIV tests screen antibodies so require a 12-week window period for an accurate result. They are also slightly less accurate than laboratory tests, (98.03% for oral and 99.68% for blood).

Rapid tests which detect both antibodies and the p24 antigen are available at some clinics but these require a sample of blood.

Q. I don’t want to go to a clinic.

A. Testing options: Home HIV sampling kits

Works from: depends on test used

Available from: online pharmacies, doctors and clinics

Accuracy: depends on test used (at least 99.5% accurate for HIV 1&2)

Over-the-counter Rapid HIV tests are currently unregulated and illegal to sell in the UK. You can however take a sample at home (a swab from inside your mouth, or a blood sample) and then send it away for laboratory testing. Your result will then be passed onto you via email, text or phone call.

The test used will depend on the clinic. Zava uses the standard HIV1&2 Abs/p24 Ag ‘4th Generation’ test for example.

Q. I tested positive, what now?

A. Options: Western blot, indirect immunofluorescence or line immunoassay

Available from: GP, GUM clinics

Accuracy: 99.9% accurate when combined with initial test

There’s a small chance that your result could be a false positive, so all positive test results must be followed up by a confirmation test. This will most likely be: a western blot assay, an indirect immunofluorescence assay or a line immunoassay.

When the two tests are combined together, there is less than a 0.1% chance of your result being inaccurate.

The doctor or nurse that informs you of your positive result will do all they can to meet your emotional needs. They will set up a meeting with a specialist (ideally within 48 hours) who talk to you about what this all means, and put you in touch with local support groups.

Q. What's emergency PEP treatment?

A. Options: PEP (Post-exposure Prophylaxis)

When can I take it: ideally less than 72 hours of exposure

Available from: GUM Clinic, A&E

Efficacy: 90%

This is not an HIV test, but emergency PEP treatment. It involves you taking anti-HIV medication for a full 28 days after exposure to lower your chances of developing an HIV infection. PEP comes with the potential for some serious side effects, it is not guaranteed to prevent HIV, and must be taken as soon as possible after exposure (preferably within 24 hours, definitely within 72 if possible) to be effective. Learn more about PEP.

Whatever test you go for, just make sure you get tested. Click here for support and advice on what to do after receiving a positive result; or here, to find GUM clinic in your local area.

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Medically reviewed by:
Dr Nicholas Antonakopoulos

Dr Nicholas Antonakopoulos graduated from the University of London in 2006. He did his postgraduate training in hospitals in the London area, and he trained for four years in Trauma and Orthopaedic Surgery before completing his training in General practice in 2015.

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Last reviewed: 19 Mar 2019

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Zava offers a convenient and discreet service to test for sexually transmitted infections. You will receive your test kit by post. Follow the instructions provided with the test kit and collect a sample (depending on the test kit this could be a blood, saliva, urine sample or genital swab). The test kit comes with an envelope, ready to send to our partner laboratory which will analyse your sample. Once your result has come back, you will be able to view it in your secure Zava account. We will never send medical or personal information via email.




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