Is a negative HIV test at 6 weeks conclusive?
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- Written by Dr. Andrea Pinto on 09 December 2021
According to the National Cancer Institute, the HIV window period is defined as the period of time that starts when someone becomes infected with HIV until the body is capable of producing enough antibodies against the virus so that it can be detected on a test. Simply put, it’s the time between getting HIV and having the infection show up on a test.
Tests that are taken before the HIV window period ends will be negative, but they can’t conclusively determine whether someone is infected or not.
If you recently had a potential exposure to HIV — such as having unprotected sex with an partner with an unknown STD status —, it can be quite nerve wracking to wait until the window period is over so you can receive an accurate test result. However, it’s very important to wait until this period is over, since a false negative can also lead to a false sense of security and delay your diagnosis later on.
Keep reading to find out whether a negative HIV at 6 weeks is conclusive.
Is a negative HIV test at 6 weeks conclusive?
The answer to this question will largely depend on the type of test that is being used, and how quickly each person’s immune system can generate antibodies against HIV. Different types of tests can be used to diagnose HIV, and you should discuss your options with your doctor if you’re ever exposed to this virus. Your physician will be able to recommend when you should get tested, and whether you should repeat the test after a certain amount of time.
According to the portal Smart Sex Resource, tests that measure antibodies produce against HIV have a window period that can range anywhere between 3 weeks to 3 months. Antibodies are proteins that your body produces in response to an infection. These tests depend on how fast your body can produce enough antibodies against HIV to be detected by the test.
These tests can be carried out by taking a blood sample at a doctor’s office. Alternatively, you can get an HIV antibody test using a finger prick blood sample, saliva, or urine samples.
Approximately 95 percent of people will develop HIV antibodies by 6 weeks, and 99 percent of people will have them 3 months after exposure. Since the window period ranges significantly with these tests, a negative result at 6 weeks may be conclusive, but in some cases, it can also be a false negative.
There is a test called fourth generation enzyme-linked immunosorbent assay (ELISA), which is a combined antigen/antibody test. This test detects an antigen called p24 antigen, which is a protein that can be found in the core of the HIV virus, in addition to testing for antibodies against HIV.
It has been estimated that 99 percent of individuals infected with HIV will test positive using a fourth generation test 6 weeks after exposure. According to Aidsmap, the median window period for this test ranges between 13 to 24 days after exposure, with an average of 18 days. However, there is an important caveat: the test can take longer to produce an accurate result if you’re using a finger prick sample, which is typically used for rapid HIV testing.
NAAT (Nucleic Acid Amplification Test)
This test looks for genetic material from the actual HIV virus in the patient’s blood. These tests are routinely used to determine a person’s viral load, which is the amount of virus in the blood. This can help differentiate between an acute and chronic HIV infection, and it can also help physicians individualize each patient’s treatment.
Approximately 90 percent of NAAT HIV tests are positive after a person gets infected with the virus, and more than 99 percent of these tests will be positive at 6 weeks if someone is infected.
Who should get tested for HIV?
As the CDC reminds us, there’s no test that can detect an HIV infection immediately after exposure. If you ever suspect that you’ve been exposed to HIV, it’s crucial that you contact your healthcare provider so you can get post-exposure prophylaxis (PEP) as quickly as possible. PEP consists of a short course of HIV medications that can prevent an HIV infection if they’re taken quickly after exposure. PEP must be started within 72 hours of exposure in order to be effective.
According to HIV.gov, it’s recommended that everyone between the ages of 13 to 64 gets tested for HIV at least once as part of their routine lab exams. Some people have a higher risk of HIV, which means that they should get tested more often.
Risk factors of HIV include:
- Having had unprotected sex with a male or female partner
- Men who have sex with men
- Having multiple sex partners
- Injecting drugs or sharing drug paraphernalia
- Exchanging sex for drugs or money
- Having a history a past STD
- Having a history tuberculosis or hepatitis
- Having a past sexual partner who had one of these risk factors
- Having a past sexual partner with an unknown sexual history
Getting an early HIV diagnosis can help keep this infection under control, since modern treatments are very effective at preventing viral replication. Thanks to these medications, patients with HIV can lead a normal life as long as they manage their disease. But for this to happen, it’s very important to get tested for HIV and other STDs regularly. You can learn more about STD testing at STDWatch.com.
HIV Window Period - cancer.gov
HIV window periods - smartsexresource.com
What is the window period for HIV testing? - aidsmap.com
Who Should Get Tested? - hiv.gov
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