Understanding HIV RNA Test: HIV Early Detection Blood Test and Where To Get One

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HIV RNA test also called HIV Nucleic Acid Testing (NAT) is one of the most precise and the quickest method available for the early detection of HIV infection. As the name of the test says, this test looks for the presence of genetic material of HIV in the human blood. Because of complexity, it remains one of the expensive tests, but with the ability to detect the virus in very short time after the exposure.

HIV RNA test is for those who would like to know about their HIV status in the shortest time after the exposure.

Table of Contents

Understanding the window period

For HIV infection to be identified by any of the available tests, one of the two conditions should be fulfilled. There must be either measurable immune response or antibodies, or a measurable number of copies of HIV. The time interval between exposure to HIV infection and ability to detect it by using tests is called window period. Logically, a good test would be one that would have shortest window period (hence able to detect infection at the earliest).

Hiv Rna Test Exposure Window Period

HIV RNA / NAT test — most accurate test for early detection

It is a test that looks for the genetic materials or RNA of HIV in the fluid being tested, and thus being most accurate and can detect HIV in very short time after exposure. It has the shortest window period of around one week, while most people can be detected for HIV status with this test within 28 days.

HIV RNA looks directly for the virus in the blood, with window period as short as three days in most cases, while majority being detectable within two weeks of exposure.

What makes this test so accurate is that it looks directly for the presence of HIV, rather than antibodies or antigens which may give false results in a small number of cases (either false negative or false positive).

Questions arise that if it is the most accurate and with shortest window period, why not use it as the first-line test in all the cases. One of the factors preventing the universal acceptation of this test is its high costs. Another problem is that this test requires specialized laboratory equipment thus no rapid or home-based testing can be done.

How much would an HIV RNA test cost?

But albeit some limitations, it is no doubt the best of the tests that one can get. Cost factor for this test is not much of a problem for developed economies like the US or EU. Depending on the laboratory, its cost would generally vary anything between 110$ to 180$, that may be several times more expensive as compared to rapid tests, but a price worth paying as it provides more accurate information.

What are the other benefits of HIV RNA test?

It is essential to understand that unlike antibody or antigen test, it is a test that not only tells if a person is HIV positive or not, but is also qualitative test. Which means that it is the only test that can tell how many of the copies of the virus are there in the blood. Thus HIV RNA test is one of the essential tests for monitoring the progress of disease and effectiveness of the treatment.

How often should a person be tested for HIV?

How often the test should be done would much depend on the risk factors. Generally, once a year would be fine for most people, but those with a higher risk like MSM (men who have sex with men), or those taking drugs (injectable drugs) should take preferably every three months or at least every six months.

HIV RNA testing procedure

It would require visiting a lab. A small amount of blood would be taken from your vein, but there is no need to worry as the process is practically painless. Your test result would be available within 1-2 days.

Other tests for HIV detection

All available tests try to detect either antibodies to HIV, or HIV antigen, or a copy of its genetic material (RNA test). Some tests could be a combination of methods.

Antibody tests - these remain the most commonly used tests globally due to their low cost. This test tries to find the antibodies in our blood to HIV. Though the accuracy of these tests is quite high (almost close to 99%), but these suffer from one major setback. Immune response as already mentioned needs time to develop, thus this test would work only after three to four weeks of infection, and in some cases, this window period could be as long as three months.

As these tests are generally cheap to conduct, therefore, these remain the mainstay of HIV screening for masses; these can be done in the laboratory. Rapid tests are also available that can give result in few minutes at the testing spot, while some of the companies have even developed the tests to detect antibodies in saliva and thus the test can be carried out even in the privacy of home.

As these tests are still not 100% accurate, generally additional tests would be done to confirm the diagnosis.

Antigen tests - one of the tests used for early detection of HIV infection is p24 antigen test. It has lower accuracy when compared to antibody tests, but has a shorter window period of about two weeks in most cases. It can be done two weeks after the exposure (in some cases even ten days). But as the HIV progresses, its accuracy decreases. Hence, this test is not useful in the late phase of exposure.

Nowadays, a combination of antibody and p24 are commonly used in laboratories (4th generation tests), thus having a window period of 2-4 weeks. These tests would generally cost between 60-100$.

Quick facts about HIV / AIDS

  • More than 1.1 million living with HIV in the US, yet 1 out of 7 does not know about it
  • Men having sex with men are at highest risk (70% new cases are among gays or bisexuals)
  • Second most common cause of HIV infection is heterosexual sex (23% of new cases in the US)
  • 7% of new cases of HIV are those injecting drugs
  • For women heterosexual contacts remains the number one cause of contracting HIV (above 80%)
  • Since the discovery of HIV in 1981, it has taken lives of more than 36 million people
  • With treatment majority of those infected with HIV can live close to a normal life
  • Therapy against HIV is more effective if started at the earliest, that is started immediately after the diagnosis

Frequently Asked Questions

What are the tests need to be done if a person is HIV positive?

HIV RNA as mentioned also helps to quantify the test, know the so-called viral load, thus it is one of the tests that is done to a person whether on medical drugs or not. Another test that would be done is CD4 count. In HIV CD4 are immune cells that go down in number with the progress of the disease, and they also help to understand the immune status of the person. Presence of HIV in blood is not AIDS (acquired immune deficit syndrome), but if CD4 cells go below a certain level, a person is said to have developed AIDS. At present CD4 count above 500 is considered more or less safe, some countries would even consider 350 to be safe. But anything below that is dangerous for life, and a person is at risk of developing opportunistic infections.

How can HIV be prevented?

Abstinence is the unpractical solution. But real way is to avoid too many unknown sexual partners and regularly use a physical barrier like condoms for prevention during the sexual act. It should be understood that after condoms remain the most efficient way to HIV prevention. But for those who for some reasons cannot use them, they may take a pill PrEP (pre-exposure prophylaxis), a pill is taken once a day may give above 90% protection. Or in case of accidental exposure PEP (post-exposure prophylaxis) can be taken within 72 hours of the exposure.

Can HIV be treated?

Yes, it can be treated with great success, though it cannot be cured. HIV medicine is one of the most progressive parts of medicine. In three decades more than thirty different drugs have been approved by FDA. Usually, an HIV positive person would be given one pill a day to kill and suppress the HIV infection. With new once-a-day tablets, one can expect to live almost close to a normal life. Thus HIV is now considered as non-fatal, chronic disease.

What does undetectable status mean in HIV positive person?

Well, modern therapy is now capable of killing most of the HIV population in the blood. Hence HIV RNA test would not show any virus in blood after a specified time (usually three to six months). But, this does not mean that person has been cured, as HIV is very clever and it hides in several locations in our body, in the brain, in certain cells in intestines. Thus one has to continue taking a pill for whole life, to prevent a resurgence of infection.

Once again in a person with successful therapy HIV RNA test form the backbone of regular monitoring as it is the only test which can tell how well the pill is working. In case of HIV resistance to drugs or resurgence of infection, it would be able to detect the increasing number of viruses in blood.

What lies in the future for HIV positive people?

Though modern drugs can eradicate the HIV in the bloodstream, however, it is able to hide in some cells of our body and may remain in them for whole life. Efforts are being made to find a treatment that could force them to come out of these hiding places, or use specialized technologies like CRISPR to remove their genetic code from our body cells.

Further, the effort is also continuing to come up with a therapeutic vaccine or maybe even usage of some other kind of immune therapy that could provide us lifelong immunity and ability to kill the virus without the use of chemical drugs.

Last but not the least, efforts are also being made to prolong the effect of drugs that are already effective against the HIV, so that person does not need to take a daily pill. Instead one can get an anti-HIV shot once a month or even every six months.

One has to understand that HIV is not a fatal illness anymore, it is quite comparable to health problems like diabetes, high blood pressure or even obesity that needs to be taken care off. Thus, secret to survival is the timely diagnosis. Among all the tests, HIV RNA test stands out with its ability to detect the virus at earliest, and has the capability to quantify the viral population in blood.

Basics about HIV

HIV is a short form of human immunodeficiency virus; it belongs to the family of viruses called retrovirus, and subgroup lentivirus. It is among the smallest of viruses, which grows and multiplies slowly, that is why the name lentivirus. Because of its slow growth it causes chronic infection and is difficult to detect in the early phases of the disease. As it remains undetected in a large number of cases, it continues to spread by infecting healthy individuals. Hence lies the importance of regular testing in a high-risk group, and need of finding the tests that are accurate and able to detect it at the earliest.

Viruses are unique micro-organisms that are something in between the living beings and inert materials. They practically keep lying like a lifeless thing in outside environment. They can only grow and multiply in living cells. But not in just any cell, every virus needs some particular type of host cells to grow and multiply. Thus HIV multiplies primarily in sub-group of our immune cells. Once it has created enough copies, it breaks that cell, thus killing it in the process. It slowly leads to a deficit of immunity, and the inability of our body to fight infections. Which if left untreated could be fatal in many cases, if not all.

Viruses also differ in a way that they contain either DNA or RNA as a genetic material. HIV contains only RNA as genetic material. Hence the test is used to detect its RNA in the blood.

How do most HIV tests work?

Let us first understand some of the terms used in diagnostics, to know how these tests are able to detect such a minute thing in blood as HIV.

What is HIV antigen?

Firstly, we have to understand what is an antigen. Textbooks would call antigen anything that can induce an immune response. But in simple words, the antigen is identifying part of any foreign material. It can be compared to face or fingerprints in humans. These specific characteristics help our immune system to recognize the enemy and decide a proper reaction.

What are HIV antibodies?

When any infection or HIV is identified by its antigen, the immune system starts producing antibodies. That is the initiation of defense reactions. These are Y-shaped proteins that are specific to every infection. Thus antibodies towards HIV infection would only work against it, while antibodies towards let’s say tuberculosis would only work against it. These antibodies can either directly neutralize the enemy, or they serve as a marker, helping another part of the immune system to kill the enemy. Here it is critical to notice that if a person has been infected by some micro-organism for the first time, the body requires time to produce antibodies and hence the immune reaction is delayed, thus explaining the longer window period of antibody-based tests.

The body of infected person needs time to identify the HIV infection and start producing antibodies. There are considerable variations in the time period required to initiate an immune response by various people, but still, most would begin tackling HIV infection after three weeks, and 95% would start producing antibodies within four weeks. However, in minority of cases, it may take anything from three months to one year.

Mark Riegel, MD
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