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Hiv Test Accuracy Window Period

What Should I Do If My At

HIV test accuracy and window period for HIV tests .

If you use an at-home rapid HIV test and get a positive result, you should immediately contact your doctor. They will likely recommend that you get a second test from a healthcare professional to confirm the results. False positives are a possibility, so you will want to confirm the tests results.

If you are at high risk of HIV, your best option is to talk to a doctor about taking PrEP. This will protect you from the risk of HIV transmission. PrEP is a medication regimen that can reduce the risk of HIV transmission by up to 99% when taken as directed.

Hiv Rna Test Compared To Other Tests

The HIV RNA test is a type of nucleic acid test . NATs are blood tests used to detect the genetic material of viruses and bacteria in your blood. Theyre sometimes used to screen blood donations for HIV and other conditions, such as hepatitis B.

The HIV RNA test is also called the HIV viral load test, since it can identify the viral load, or how much genetic material from HIV is in your blood. This sets it apart from other HIV tests.

According to the , there are two other types of HIV tests:

  • HIV antibody tests. These tests look for antibodies created by your body in response to HIV.
  • HIV antigen/antibody tests. These tests look for antibodies, but they also look for antibodies and an HIV protein called p24.

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How Accurate Is An Hiv Test After 2 Weeks

It will depend on the type of HIV test. Generally speaking, HIV tests are highly accurate when theyre performed correctly and after the proper window period.

An antibody test may not be accurate after 2 weeks because it typically takes the body a few weeks or even months to produce HIV antibodies.

An antibody/antigen test can technically detect HIV in as little as 18 days, or about 2.6 weeks.

According to a 2017 study, only 25 percent of people with HIV will receive a positive test result within 13.0 to 14.8 days of taking an antibody/antigen test. After 17.8 to 19.2 days, that ratio improves to 50 percent. After 43.1 to 44.3 days, the test will detect HIV in 99 percent of HIV-positive people.

An RNA test can detect HIV in 10 to 14 days, according to the San Francisco AIDS Foundation. The National Cancer Institute states that an RNA test can detect HIV .

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Which Hiv Test Is The Most Accurate

When it comes to choosing the most accurate HIV test, both rapid and lab tests detect HIV with more than 99% sensitivity and specificity. That means theyll miss fewer than one out of every 100 people who actually have HIV, and fewer than one out of every 100 people without HIV will be given a false-positive result. The main difference between the tests is how long you need to wait to get an accurate result.

Rapid HIV test accuracy can be lower if youre still within the window period. Its not necessarily that the test is inaccurate. Its the timing of the test related to the exposure, says Promer.

NAT has the advantage of detecting HIV as soon as 10 days after infection. Some people may wonder, Why dont we just do that up front? she adds. Then explains, Its kind of resource-intensive and expensive. And the benefit is really just over a short period of time.

To pick up a very early infection, an antibody/antigen test plus an NAT test is the most reliable choice. For everybody else, I think the standard antigen/antibody test would suffice, Urbina says.

Hiv Rna Test Cost With Insurance

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Many health insurance policies in the U.S. do not cover the HIV RNA test cost. They might only cover the cost of the advanced tests performed. The coverage also depends on your insurance plan as some national insurance programs recommend HIV screening once a year and they cover the cost of HIV screening tests.

Our HIV RNA testing providers offer screening tests for HIV infection and do not accept any health insurance. But, they can provide you with an itemized receipt containing all the details like the name and code of the test, and CPT code which is necessary for insurance reimbursement purposes.

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What Serological Tests Are Available For Hiv

Since the US Food and Drug Administration approved the first HIV diagnostic test in 1985, four additional generations of antibody tests for HIV have been developed each improves incrementally on its predecessor in terms of performance and shortening of the window period3,8 . The official nomenclature for HIV testing is currently changing, with categorizations based on analytic target instead of generation numbers.9 For example, first- and second-generation assays are now referred to as IgG sensitive, since they are capable of detecting only IgG. Each category of tests may be further subcategorized as point-of-care or laboratory-based .

HIV serological tests

In IgG sensitive tests, anti-HIV IgG from a patients specimen binds to immobilized HIV antigens on the solid phase of the assay detection most often uses protein A conjugated to colloidal gold. IgM/IgG sensitive tests permit binding of both IgM and IgG from specimens, with detection accomplished using labeled, synthetic HIV antigens . The addition of simultaneous, monoclonal antibody-mediated p24 antigen detection distinguishes Ag/Ab combination assays from IgM/IgG sensitive tests.

How Long Are The Window Periods Of Different Hiv Tests

It is hard to say exactly how long the window period lasts, as there are variations between individuals and it is a difficult topic to research .

Nonetheless, a study by Dr Kevin Delaney and colleagues calculated window periods for a range of HIV testing assays. All these analyses were based on plasma samples. Window periods are likely to be several days longer when testing samples of fingerprick blood or of oral fluid, as will be normal when using rapid, point-of-care tests and self-testing devices. Unfortunately, precise figures for how much longer the window periods are have not yet been published.

The researchers analysis confirms that fourth-generation laboratory tests detect HIV infections between one and three weeks earlier than older antibody-only tests. Moreover, their data suggest that some countries guidelines which recommend retesting 90 days after a possible exposure to HIV are more cautious than they need to be.

Afourth-generation laboratory testis recommended in UK and US guidelines. It uses a sample of blood plasma or serum and can detect immunoglobulin G antibodies, immunoglobulin M antibodies and p24 viral antigen . Commonly used tests of this type include Abbott Architect HIV Ag/Ab, GS Combo Ag/Ab EIA and Siemens Combo HIV Ag-Ab.

  • The median window period is 18 days . This indicates that half of all infections would be detected between 13 and 24 days after exposure.
  • 99% of HIV-infected individuals would be detectable within 44 days of exposure.

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What Are The Different Types Of Hiv Tests

The window period and accuracy for HIV testing varies by test and the bodys individual immune response. The following are types of HIV tests, window periods for each, and accuracy information.

Generally, tests that use blood from a lab draw deliver accurate results sooner than tests that use finger pricks or oral swabs.

Window Period When Should You Get The Hiv Rna Test

4th generation hiv test window period (and test accuracy)

The HIV RNA test is called the early detection test because its window period is far shorter than other types of HIV tests. After a person is exposed to a possible HIV infection, they cannot take a test until they reach the window period for the test. This phrase is used to describe the time after which the test can actually start to work.

If you take a test too soon, it may not bring up any results even though you are infected with HIV. Unlike other tests, HIV RNA testing can be done just 9 to 11 days after you are exposed to HIV. Results are almost always reliable at 9 days following exposure, but you can wait until 11 days if you want to be on the safe side.

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Accuracy For Types Of Tests

The window period for each type of HIV test is as follows:

  • Nucleic acid test : A NAT can tell if you have HIV infection 10 to 33 days after exposure.
  • Antigen/antibody test: An antigen/antibody test can usually detect HIV infection 18 to 45 days after exposure. Antigen/antibody tests done with blood from a finger prick take longer to detect HIV, usually 18 to 90 days after an exposure.
  • Antibody test: An antibody test can take 23 to 90 days to detect HIV infection after an exposure.

Window periods vary from person to person, so some clinics may advise you to wait a certain time.

  • One to three weeks before getting a NAT
  • One month before getting a combination HIV Ag/Ab test
  • Three months before getting any other HIV tests

Where Can People Find Free Hiv Testing Locations

The CDC maintains a list of HIV testing locations for people who want to find out whether they have contracted the virus. This National HIV and STD Testing Resource can be accessed at . This site includes the ability to search for free testing locations as well as locations that provide rapid tests. Some clinics only provide HIV testing. However, sexually transmitted diseases clinics routinely provide HIV testing along with testing for diseases like chlamydia, gonorrhea, syphilis, and herpes.

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First Stage: Acute Hiv

Acute HIV usually shows little-no symptoms of the disease. Fever, headache, and fatigue which flu-like symptoms shown in the first stage. It may take up to 2 3 weeks for the symptoms to occur after the initial exposure. In the Acute stage, the HIV virus is in tiny quantities that make the regular tests undetectable. You may not experience the symptoms until the virus gets manipulated massively. Some people will get to know only when the infection reaches the Chronic HIV stage.

Symptoms of Acute HIV infection include

When To Test After Pep


Meanwhile, for PEP, the CDC states that people should be tested for HIV immediately after completing their course of PEP medications . After this, it is recommended that they get tested again at three to six months post-exposure to fully confirm that they are HIV negative, according to Chanel Marshall, M.S., an HIV health educator with Inova Health System. However, It is always best to consult with your health care provider for an individualized plan, she notes.

All in all, its unlikely that modern-day HIV testswhether theyre HIV antibody tests, HIV antigen tests, or HIV viral load testswill be affected by taking PEP or PrEP. The best advice we can give is to follow CDC guidelines and speak to your health care provider if you are concerned.

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Testing After An Exposure Event

HIV testing is often prompted by a defined exposure, such as a needlestick injury, condom failure, or condomless sex. Because no diagnostic test is capable of detecting infection in the eclipse period, baseline testing is obtained to rule out undiagnosed, pre-existing infection in the patient. Blood-based POC testing should be used whenever possible, in order to facilitate prompt initiation of post-exposure prophylaxis .26,27 Strong preference should be given to an Ag/Ab combination test over antibody-only options, and oral fluid should not be used. Follow-up testing should occur 46 weeks and 3 months after baseline, with additional testing at 6 months if the exposure event resulted in hepatitis C virus infection.27 If the patient tests negative at the end of the window period , one can be very confident that s/he did not acquire HIV from the exposure.

Timing Of Serological Testing In Infants

The most recent advances in EIA technology have produced combination assays, which allow for the simultaneous detection of p24 HIV antigen and HIV antibodies. This approach has further shortened the window period, i.e. the interval between HIV infection and detectable HIV antigen/antibodies. Rapid tests appear to offer similar performance characteristics but they detect antibody 28 days later than third-generation EIAs.

All children born to HIV-infected mothers carry detectable maternal HIV antibody and this declines slowly over the first year of life. The rate of decay of maternal antibody has been ascertained largely by analysis of studies to detect HIV antibody in children who have not been breastfed. The mean and/or median age at the time of seroreversion ranges between 9 and 16 months of age in studies from both developed and developing countries . These data indicate that maternal antibody may remain detectable through the first 6 months of life but significant decay occurs by 912 months of age. Most HIV-uninfected children do not have detectable antibody at 12 months of age .

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How Do Hiv Tests Work

There are two basic ways to get HIV test results:

Laboratory tests. For these tests, a technician will take a sample of your blood and test it. Youâll get results within a few days.

Rapid tests. These tests provide results in around 20 minutes. You can get them done in a community clinic or take them at home.

What Is The Window Period

what is a 4th generation hiv test? – accuracy, window period.

The window period is the amount of time between your exposure to HIV and when the test is able to detect the virus or your immune systems response to it. Right after HIV transmission, the virus is at levels too low for even the most sensitive test to pick up because it hasnt multiplied enough in your body to be detectable, and your body hasnt yet mounted a response against it.

The window period ranges from 10 days to 90 days, depending on the test you take.

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Figure : Time To Develop Antibodies *

95% people by week 4, 99% by week 6 and more than 99.9% by week 12

Figure 8 shows the range of times that people can take to respond to HIV infection.

The earliest marker is HIV viral load. This is in the first weeks after infection . A high viral load is related to seroconversion symptoms.

The first HIV protein that can be measured is p24 .

Viral load and p24 tests are not accurate for diagnosing early HIV if the results are negative.

An HIV antibody response can be detected as early as two weeks in a few people and in more than 99.9% of people by 12 weeks. An antibody test at 4 weeks will detect 95% of infections.

Antibody testing at 4 weeks can give you a good indication of your HIV status, but you need a test at 12 weeks after the exposure to be considered HIV negative.

Outreach Testing In Developed Countries

Mobile testing units, syringe exchange programs, and community testing events place a premium on test portability, ease of administration, flexibility in specimen type, and rapid turnaround of results all of which make POC tests an obvious, frequent choice. However, longer window periods and lower sensitivities with POC assays compared to their laboratory-based counterparts are important trade-offs to consider. Because some outreach testing populations may be more likely to have recent HIV infection, IgM/IgG sensitive POC tests should be prioritized over those capable of detecting IgG only. Whenever logistically feasible, serum or plasma should be tested instead of whole blood, and consideration should be given to sending a specimen for laboratory platform testing in addition to the POC test. Oral transudate should be used as a specimen only when obtaining blood is impractical or undesirable.13 Patients and testing clients considering oral HIV self-testing should be counseled about its longer window period compared to either blood-based POC tests or laboratory-based assays.

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Dried Blood Spot Test

A DBS test is a free, accurate and convenient way to test for HIV in the comfort and privacy of your home.

It involves collecting a few drops of blood from your finger and allowing the blood to dry on a test card. You then send the card away to get tested and wait around a week to get the result back. You can register for a DBS HIV test here.

How Soon Can A Blood Test Detect Hiv


The window period is when a person is first exposed to HIV and when the virus will show up on types of HIV blood tests.

The window period can last 10 to 90 days, depending on their bodys immune response and the type of test that theyre taking.

A person may receive a negative test result during the window period even though theyve contracted HIV.

A person can still transmit HIV to others during this window period. Transmission may even be more likely because there are higher virus levels in a persons body during the window period.

Heres a quick breakdown of the types of HIV tests and the window periods for each.

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Are These Figures Always Accurate

In some situations, these figures should be interpreted with caution:

  • When tests are done with samples of fingerprick blood or oral fluid , their window periods are likely to be longer.
  • Individuals who are taking pre-exposure prophylaxis or post-exposure prophylaxis may have a delayed antibody response, extending the window period.
  • The data are based on individuals with HIV-1 subtype B and its possible that tests are less sensitive to other subtypes.

British HIV Association, British Association for Sexual Health and HIV and British Infection Association. Adult HIV Testing Guidelines 2020.

Delaney KP et al. Time from HIV infection to earliest detection for 4 FDA-approved point-of-care tests. Conference on Retroviruses and Opportunistic Infections, abstract 565, 2018.

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