HIV Test Types And The Accuracy Of Their Results

The rumours are true, I am a weird scarlet-haired combination…

Whether you think you might have been infected with HIV or any other STD, testing is an important step for your health, your relationships, your life, and your future. Taking an early HIV test and detection will help towards slowing down or stopping the progress of your infection with early treatment.

Before we go any further with HIV testing and its types, let’s learn some basic information about HIV/AIDS. HIV stands for human immunodeficiency virus. It is a virus that can lead to AIDS (Acquired immunodeficiency syndrome). HIV attacks the body’s immune system, our natural defense against pathogens, infections, and illnesses. The virus attacks and destroys CD4, a type of white blood cell also called the T-helper cell, that gives you an indication of the health of your immune system and leads the attack against infections or illnesses. So, the lower the CD4 cell count, the weaker the immune system. This means that people infected with HIV will find it harder to fight off infections and diseases without a proper treatment.

If this virus is left untreated, 10 to 15 years will be enough for the immune system to be so severely damaged that it can no longer defend itself at all. And eventually, opportunistic infections or cancers take advantage of your weak immune system and signal that you have AIDS, which is the last stage and the most severe phase of HIV. However, the rate at which HIV progresses varies in people of different ages and their general health.

HIV AIDS is classified as an STD because it can get spread through sexual contact or through certain body fluids. You can read more about STDs, their causes, prevention, diagnosis, and treatment here.

Who should get tested for HIV?

The safest way through which one can know if you have been infected with the human immunodeficiency virus is to get tested. Being informed earlier about your condition helps you make healthy decisions to prevent getting infected with the virus or transmitting it.

The Centers for Disease Control and Prevention (CDC) suggests that every person from 13 to 64 years old should get tested for HIV at least once as part of routine health care. Sexually active persons and people at high risk, in general, should get tested every year. Whereas, gay and bisexual men should get tested every 3 to 6 months, because of being more prone to the risk of HIV infection.

People are considered at high risk for HIV infection, due to the list of factors below:

Having sexual intercourse with an HIV positive person without using condoms

Sharing needles, syringes, or other drug tools with other persons (if the temperature and other factors are suitable, the virus can survive in a used needle up to 42 days)

Having hepatitis or tuberculosis, or an STD, such as syphilis

Having sexual contact with persons who have any of the above-mentioned HIV risk factors

It’s always important to talk to your health care provider about how often you should get tested for HIV.

What are the types of HIV tests?

HIV testing can detect HIV infection, however, it can’t show for how long one has been infected with the virus or if the person has reached the AIDS stage.

There are three types of HIV tests available, which are:

Nucleic acid HIV test (NAT)

The nucleic acid test is a test which detects the genetic material of a microorganism, in this case HIV, in the blood. NAT can show either a positive or a negative result or the amount of virus in the blood. The latter one is measured through the Viral Load Tes (HIV RNA), which is a type of nucleic acid test. NAT is a very expensive method and not routinely used for screening individuals without having been exposed to a high-risk situation or notice early symptoms of the infection. NAT is usually done in the first stages of infection before the body has started producing antibodies in response to the virus.

It is recommended that even if you got a negative result of NAT you should get an antibody or antigen/antibody test to make sure the result is valid. Taking medicines to lower your chances of getting infected, such as pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP) might lower the accuracy of NAT if you are already infected with the virus.

Antigen/antibody HIV test

An antigen/antibody test searches for both HIV antibodies and antigens. When your body is exposed to bacteria or viruses, your immune system produces antibodies to fight them off.

Antigens are foreign substances or particles, usually proteins, which stimulates your immune system by activating lymphocytes, which are a type of white blood cells which fights infections. So, if you are infected with HIV, the antigen called p24 is produced even before antibodies develop.

So, the HIV p24 antigen test detects the p24 protein on average 10 to 14 days after infection with HIV. One barrier of this type of test is that levels of the p24 protein peak at around 3 to 4 weeks after exposure to the virus and cannot be usually detected after 5 to 6 six weeks. A positive p24 test means that someone is HIV-positive. However, a negative p24 test can mean three things:

– the person is not infected (HIV-negative)

– the person is infected with HIV (HIV-positive), but the test could not detect the p24 protein because the person was infected more than 4 to 6 weeks earlier

– the number of p24 antigens is too low to get detected

However, there is a more advanced HIV test, which combines a p24 antigen test and an antibody test. The combination of the two detects the p24 antigen levels with the accuracy of the newer antibodies.

Antibody HIV test

Antibody tests detect the antibodies a.k.a the white blood cells which protect your body against infections. An antibody HIV test is the fastest method to detect HIV infection. This kind of test uses blood from your vein or finger or oral fluid oral. Nevertheless, tests that use blood from veins detect HIV sooner than two latter methods.

This kind of test is also called immunoassay or ELISA test. It is generally very accurate, but it doesn’t catch early infections.
Except for the blood, some immunoassay tests also check your urine or fluids from your mouth (not saliva), but because the antibody levels are very low there, you may not get a positive result even if you’re infected. (known as a false negative.)

However, there are options for taking an HIV test in the privacy of your own home. Currently, there are two home HIV tests: the OraQuick In-home HIV test and the Home Access HIV-1 Test System. In case you purchase your HIV test online, make sure the HIV test is FDA-approved.

The OraQuick In-Home HIV Test provides results in about 20 minutes. The testing procedure involves swabbing your mouth to collect an oral fluid sample and using a kit to test it. If the results are positive, you will need to undergo a follow-up test. This due to the lower amount of antibodies in oral fluid.

On the other hand, the Home Access HIV-1 Test System is a home collection kit, which involves pricking your finger to collect a blood sample. After, you have to send the sample to a licensed laboratory, and then wait a business day to call in for results. The test is anonymous.

This kind of test find HIV infection later than other lab-based tests using blood from a vein, but earlier than tests using oral fluid.

Whether you undergo a home HIV test or a test conducted in a lab, if the first test shows a positive result, you will need a follow-up test to confirm the result.

How soon after an exposure to HIV can a test detect HIV?

The period between when a person may have been exposed to HIV and when a test can show a valid result is called the window period. This period differs depends on the person and type of HIV test.

A nucleic acid HIV test (NAT) can usually tell you if you have HIV infection 10 to 33 days after an exposure.

An antigen/antibody HIV test conducted in a laboratory on blood from a vein can usually detect HIV infection 18 to 45 days after an exposure. Whereas, when the test involves collecting blood from a finger prick can take 18 to 90 days after exposure to detect HIV. If you want a more reliable result, tests that use blood from a vein are preferred.

An antibody HIV test usually takes 23 to 90 days to detect HIV infection.

Always talk to your health care provider to see what type of HIV test is right for you.

Is HIV testing confidential?

HIV testing can be confidential or anonymous.

Confidential testing means that your HIV test results include your name and other identifying information, and the results will be included in your medical record. If you are HIV-positive, your test result (without the personal information) will be provided to local or state health departments for statistical reports. Therefore, your test results will be used for reporting purposes only and your personal information will be confidential.

Anonymous testing means you don’t provide your name or any other personal information when taking an HIV test. All you need is a number. Before taking the HIV test, you will get a number. To get the results, instead of your name you will use the number which was given to you.

Where can I get tested for HIV?

HIV testing is available at many hospitals, medical clinics, and community health centers. A home HIV test is also available to purchase online, or you can buy at a pharmacy.

Recommended: Talk to your health care provider about your HIV risk factors and the best type of HIV test for you. If you are HIV-positive, talk to your health care provider about treatment options, and if you are HIV-negative, always take the proper steps to protect yourself from HIV infection.

Disclaimer: The contents of this article: text, graphics, images, and other materials contained are strictly for informational purposes only. The Content is NOT intended to be used as a substitute for professional medical diagnosis, advice, or treatment. Please ALWAYS seek the advice of a qualified health provider with all the questions that you have related to, or about, a medical condition.