As someone working in HIV or STDs, you may be hearing more about RNA testing. It is also called PCR testing or NAAT (nucleic acid amplification testing). RNA testing detects HIV at an earlier stage than standard antibody testing. This fact sheet explains RNA testing and will help you answer questions from patients or clients.
There are several ways to test for HIV. The most standard HIV tests don’t look for the actual virus but rather antibodies to the virus. RNA tests, however, find the HIV virus itself by looking for its genetic material (RNA). It can also tell how much HIV is there, which is called “viral load.” When people living with HIV talk about getting their “viral load tests,” they are talking about a version of this RNA test.
Comparing antibody and RNA tests
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HIV antibody tests are the most common and standard tests for HIV. They can test blood or oral fluids. The samples are tested at a lab or through on-site rapid tests. These tests look for antibodies made by the immune system in response to HIV. It takes about 1 month (sometimes up to 3 months) after infection for enough antibodies to show up on a test.
This time between infection and when it will actually show up on a test is called the window period. During the window period, a person does in fact have HIV but not enough antibodies yet to show up on an HIV antibody test. If a person has an antibody test during this window period, the results may not be accurate.
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RNA/PCR/NAAT Test
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Antibody Test
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Looks for
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actual HIV virus
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antibodies to HIV
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Window period
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1 - 2 weeks
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1 - 3 months
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Options for testing
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blood, no rapid
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blood, oral, rapid
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Wait time for results
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1 - 3 weeks
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1 week, 20 minutes for rapid
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RNA tests look for the actual virus, not antibodies. Therefore, they can reveal HIV infection within 1 - 2 weeks. However, the RNA tests are more complex for the lab to process, so it takes longer to get RNA test results.
RNA testing is not a substitute for antibody testing. It’s a good additional test for those who may have had a recent risk (within the past 1 - 4 weeks) for HIV.
Don’t confuse “RNA testing” with “rapid testing.” Rapid tests are antibody tests that can give results in 20 - 30 minutes. Rapid results, however, are only preliminary. It may take a week to get the results of the follow-up confirmation test.
Acute HIV infection and RNA testing
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When HIV enters the body, the immune system needs time to mount a good response. During this time, HIV is able to copy itself very quickly, so the amount of virus, or viral load, is very high right after infection. This 2 - 4 week period after infection is called “acute infection.” Only tests that look for the actual virus, like RNA or antigen tests, can detect HIV infection during this time.
Acute HIV infection occurs during the window period for the antibody test. Once the immune system starts making antibodies and attacking HIV, the amount of HIV drops to a lower, more stable level.
Symptoms of acute HIV infection
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Within the first month after infection, about half of all people infected have at least one of the following symptoms:
| fever |
fatigue |
rash |
| sore throat |
headache |
night sweats |
| diarrhea |
nausea |
vomiting |
| swollen tonsils and/or other lymph nodes |
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| joint or muscle ache |
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Symptoms can last up to two weeks. If a person has one or more of these symptoms after doing something risky (e.g., needle sharing or unprotected sex with a high-risk partner) he should get an antibody test and ask about an RNA test. An RNA test can detect HIV during acute infection even if a person has no symptoms.
Diagnosing early infection is important!
- With early diagnosis, people can take better care of their health and may have more treatment options.
- They can also take steps to avoid giving HIV to others. People may be up to 10 times more likely to infect their sex partners during the first few months after getting HIV. This is partly due to the very high levels of HIV in the blood.
Where is RNA testing available?
RNA testing is available in
King
County
for all gay, bisexual and other men who have sex with men (MSM) who test for HIV at these locations:
- STD Clinic at Harborview
-
Gay
City
Health Project
- downtown needle exchange
- bathhouses
Other individuals at high risk for HIV (e.g., people who have sex or share needles with a partner who has HIV) who have symptoms of acute infection may be able to get RNA testing on a case-by-case basis through Public Health. Most private doctors can provide RNA testing, but the patient will pay a fee.
How is RNA testing done?
RNA testing requires a blood sample. Finger stick or rapid versions are not yet available.
Can you get an RNA test along with a rapid HIV antibody test?
Yes. After the rapid test, you will have to give a blood sample for RNA testing. If blood is collected for some other reason (like syphilis screening), it can also be used for RNA testing.
How long does it take to get results?
It takes longer to get RNA results because RNA tests are processed differently than antibody tests. Some RNA results may come back in 1 week, but 2 weeks is the average.
How reliable is an RNA test?
Both RNA and antibody tests can sometimes produce false-positive results. False-positive RNA test results occur in 2.6 - 5% of testers, depending on how common HIV infection is in the population. People who test RNA-positive should have a repeat blood draw and an antibody test (after the window period) to confirm RNA results.
Can an RNA test be anonymous?
Yes. The testing provider can discuss the pros and cons of both confidential and anonymous testing. Confidential testing is the best way to assure people will get their results.
For more information on RNA testing, call the HIV/STD Hotline at 206-205-7837.
