Instant HIV Test

The Instant HIV test searches for the presence of HIV 1&2 antibodies and the p24 antigen within the blood.

After exposure to HIV, your immune system will begin to produce HIV antibodies as a response to the infection. This process is called seroconversion and occurs in the weeks following HIV exposure. The antibodies generated by the immune system are responsible for targeting the virus.

During the early stage of HIV infection, there is a high concentration of p24 antigen, which is a structural protein found in the HIV viral core. This antigen is detectable in the blood for a brief period before seroconversion takes place, after which it gradually decreases.

Due to its ability to test for the p24 antigen, the Instant HIV test is able to detect an HIV infection before the immune system begins to produce antibodies.

The term ‘serological’ refers to tests that analyse blood serum (the clear liquid portion of blood). The Instant HIV test is a serological test that detects both HIV 1&2 antibodies and p24 antigen, providing a comprehensive assessment of your HIV infection status.

If you are considering this test you should ideally wait for 45 days after exposure before being tested in order to confidently rule out HIV and remove the need for further testing.

After an HIV infection occurs, it typically takes about 2 to 4 weeks for the body to start producing detectable levels of the p24 antigen. During this time, the virus replicates rapidly, leading to an increase in the concentration of p24 antigen in the blood.

As the immune response progresses, the levels of p24 antigen begin to decline and eventually become undetectable, usually around 4 to 6 weeks after infection. It's important to note that the exact timing can vary from person to person, and some individuals may have detectable p24 antigen for a slightly longer or shorter period.

After the p24 antigen levels drop, it typically takes the body a few weeks to start producing detectable levels of HIV antibodies. The exact timing can vary from person to person, but on average, antibodies become detectable within 3 to 12 weeks after the initial infection.

However, the Instant HIV test can detect HIV antibodies 45 days after exposure to the virus. This is because the majority of people with HIV have detectable levels of antibodies at this time.

PrEP (Pre-exposure Prophylaxis) and PEP (Post-exposure Prophylaxis) medications are known to interfere with the performance and interpretation of the HIV antigen and antibody test results by altering the amount of virus in the blood, and potentially delaying the development of antibodies.

Furthermore, these medications will particularly affect the level of p24 antigen, causing it to either appear for a shorter period of time at a smaller level, or not appear at all.

If you are currently taking PrEP or PEP, you should take the Instant HIV test 45 days after completing your course of medications for a reliable and conclusive HIV result.

The Instant HIV test is a highly reliable test. The specificity (% of true negatives) is 100%, and the sensitivity (% of true positives) is 99%.

In the event that your Instant HIV test is reactive, we will always confirm with a complimentary HIV-1 RNA PCR test and will send your sample to an external laboratory for confirmation.

The Instant HIV test and the HIV-1 RNA PCR test are both diagnostic tests used for detecting an HIV infection but they differ in their approach and the information they provide.

The Instant HIV test detects HIV 1&2 antibodies and the p24 antigen, a protein present in the HIV-1 virus. This test is commonly used as a screening test and can provide reliable results at 45 days and onwards after exposure.

On the other hand, the HIV-1 RNA PCR test detects the genetic material (RNA and proviral DNA) of the HIV-1 virus itself. This test measures the amount of HIV-1 RNA present in the blood. It is highly sensitive and can detect an HIV infection before antibodies are produced. The HIV-1 RNA PCR test can provide accurate and reliable results at 10 days after exposure.

You can read more about the HIV-1 RNA PCR test here.

A physical examination is not routinely required for the Instant HIV test. However, if you are concerned about experiencing HIV symptoms, we can certainly offer you an examination during your consultation for your immediate reassurance.

We recommend testing every 3 to 12 months but this depends on your personal situation. You can discuss with your clinician regarding how frequently you should test if you have more than one sexual partner, change partners frequently, engage in chem-sex or any other risks that can increase your chance of getting HIV.

However, even if you are in a mutually monogamous relationship, you may seek reassurance with routine screening, especially if you are planning to conceive. Routine NHS antenatal tests include HIV testing.

Here are a few tips on how to prepare for your appointment:

• Drink enough water so that your veins are more prominent and easy to find.
• Wear a loose fitting shirt or a short sleeved t-shirt so that the clinician can easily access your veins.
• If you have any phobias of medical places or needles, please let our receptionists know at the time of booking your appointment.
• Relax, Clarewell Clinics is a safe space. Your medical history with us is completely confidential so you can be as open and honest as you wish to be with us.
• You will not need to make any extra precautions, and will be able to continue your day as normal.

Yes. Everything you share with us is confidential and will not be shared with the NHS, your GP or anyone else unless you wish for us to do so.

The Instant HIV test results are available within 30 minutes. This allows enough time to cross check your results and repeat the tests if necessary.

A reactive result is always repeated, confirmed, and subjected to further testing before being shared with the patient.

You can receive your Instant HIV test results by either text or email.

Your Instant HIV test results will either be reported as:

• ‘NOT Detected’ (i.e. negative): You do not have HIV.
• ‘Reactive’: Instant tests are designed to be highly specific (i.e. highly accurate when it comes to providing negative results). However, a reactive test result is always provisional and subject to further testing.
• ‘Equivocal’: The test has been repeated twice but the results are invalid, thus requiring further testing.

If your results are reactive or equivocal, we will undertake an HIV RNA PCR test (at no additional cost) to check for the genetic material of the virus, and the results will be available within 4 hours.

Your results are conclusive at 45 days and onwards following your exposure. However, if you are on PrEP or PEP further testing will need to be repeated.

If you are currently taking PrEP or PEP, you should take the Instant HIV test 45 days after completing your course of medications for a reliable and conclusive HIV result.

Your clinician will advise whether your reactive test result is provisional or has been confirmed as positive through further testing.

If a positive result has been confirmed, it is essential to inform all of your sexual partners so that they can get tested and treated appropriately. Your clinician will be able to advise and support you in this matter.

If you have had unprotected sex with a partner within the previous 72 hours, your partner should immediately visit a sexual health clinic or A&E in order to access PEP (post-exposure prophylaxis) for HIV. Please note that the eligibility for PEP is subject to the clinician’s discretion.

Yes, we provide a certificate of testing.

Please let us know at the time that you would like a certificate of testing and bring a proof of ID (passport or driving licence).