Wednesday, July 17, 2024

Antigen Hiv Test Window Period

How The Oraquick In

List of HIV tests & window period associated with them – Dr. Ramakrishna Prasad

What is the OraQuick In-Home HIV Test and how does it work?

The OraQuick In-Home HIV Test is a rapid self-administered over-the-counter test. The OraQuick In-Home HIV Test kit consists of a test stick to collect the specimen, a test tube to insert the test stick and complete the test, testing directions, two information booklets , a disposal bag and phone numbers for consumer support.

This approved test uses oral fluid to check for antibodies to HIV Type 1 and HIV Type 2, the viruses that cause AIDS. The kit is designed to allow you to take the HIV test anonymously and in private with the collection of an oral fluid sample by swabbing your upper and lower gums with the test device. After collecting the sample you insert the device into the kits vial which contains a developer solution, wait 20-40 minutes, and read the test result. A positive result with this test does not mean that an individual is definitely infected with HIV but rather that additional testing should be done in a medical setting to confirm the test result. Additionally, a negative test result does not mean that an individual is definitely not infected with HIV, particularly when exposure may have been within the previous three months. Again an individual should obtain a confirmatory test in a medical setting.

When should I take a test for HIV?

How reliable is the OraQuick In-Home HIV Test?

OraQuick In-Home HIV Test Fact Sheet

Where To Get Tested For Hiv

Getting an HIV test is easy. Tests for HIV and other STIs are confidential and available from your local doctor , or a sexual and reproductive health clinic.

It is a good idea to have some pre-test counselling. Before the test, talk with your doctor, nurse, or peer tester about any concerns, your level of risk, whether you are likely to be HIV-positive and what a positive result may mean.

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Summary And Recommendations For Specific Situations

Selecting an HIV test for a given situation requires balancing client characteristics and programmatic concerns against test performance .25 At the client level, variation in individual preferences and testing patterns comes into play. Some individuals may be less willing to provide blood samples or to return at a later date for a test result, both of which have implications for selecting a POC test over a laboratory-based platform. Program-level considerations include building or maintaining laboratory capacity, training and supervising personnel, assuring quality, following up with clients, complying with local public health reporting requirements, and budgeting. With this framework and the data presented in mind, let us consider four specific situations: testing after an exposure event, screening populations at high risk of infection, outreach testing in developed countries, and selection of HIV tests for global health research.

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Newer Improved Hiv Tests Allow For Earlier Hiv Detection

HIV tests have improved substantially over the years, and are now easier and less expensive, with a more rapid turnaround time for results.1

Three types of HIV tests are available:

  • Nucleic acid tests detects HIV ribonucleic acid
  • Antigen/antibody combination tests detects HIV p24 antigen as well as HIV immunoglobulin M and immunoglobulin G antibodies
  • Antibody tests detects HIV IgM and/or IgG antibodies

Following an exposure that leads to HIV infection, the amount of time during which no existing diagnostic test is capable of detecting HIV is called the eclipse period.2

The time between potential HIV exposure and an accurate test result is referred to as the window period. Improvements in testing technology continue to reduce the detection window period, and, therefore, the time to diagnosis and treatment of early HIV infection. As seen in the figure, each type of HIV test has its own testing window, with the NAT capable of detecting HIV the earliest, followed by the antigen/antibody combination test, and lastly, the antibody test.

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Testing Recommendations And Requirements

HIV test 4th Generation in Fukuoka with Q& A

The U.S. Centers for Disease Control and Prevention recommends routine HIV screening in health-care settings for all adults, aged 13-64, and repeat screening at least annually for those at higher risk.26,27 Per the CDC individuals who may benefit from at least annual screening include:28

  • sexually active gay or bisexual men
  • individuals who have had sex with an HIV-positive partner
  • individuals who have had more than one partner since their last HIV test
  • those who have shared needles or works to inject drugs
  • people who have exchanged sex for drugs or money
  • individuals who have another sexually transmitted disease, hepatitis, or tuberculosis
  • those who have had sex with someone who has participated in any of the above activities or with someone with an unknown sexual history

Certain factors are known to reduce the risk of HIV transmission including condom use, antiretroviral treatment leading to durable viral load suppression among those with HIV, which prevents further transmission, and the use of pre-exposure prophylaxis among those at increased risk for HIV.29

Additionally, HIV testing is recommended for all pregnant women and for any newborn whose mothers HIV status is unknown.30 Treatment provided to pregnant HIV-positive women and to their infants for 4-6 weeks after delivery can reduce the risk of transmitting HIV to 1% or less.31 HIV testing is also recommended for anyone who has been sexually assaulted.

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Stages Of Hiv Infection

HIV infection is categorized according to the severeness of the symptoms exhibited.

The first stage is termed Acute HIV infection where the virus has just entered the body and begun to manipulate.

The second stage is known as Chronic HIV, this is the stage when some people start experiencing actual symptoms of the disease, by now the infection has started to spread rapidly.

The final stage is known as AIDS , where the immune system is totally weakened and the infected person is open to acquire any disease otherwise a healthy person does not get affected easily.

How Soon After Exposure To Hiv Can An Hiv Test Detect If You Are Infected

No HIV test can detect HIV immediately after infection. If you think youve been exposed to HIV, in the last 72 hours, talk to your health care provider about post-exposure prophylaxis , right away.

The time between when a person gets HIV and when a test can accurately detect it is called the window period. The window period varies from person to person and also depends upon the type of HIV test.

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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

How Do Hiv Tests Work

What is the maximum window period for HIV test in India? – Dr. Ramakrishna Prasad

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.

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How Soon After Exposure To Hiv Can A Test Detect The Virus

HIV tests cant detect HIV immediately after youve been exposed. It takes time for your body to make antibodies in response to the virus. The window period is the time gap between when you were exposed and when a test can detect the virus. Youll want to get tested after the window period. The window period varies from person to person and by the type of test.

  • A nucleic acid test has the shortest window period. It can tell if you have an HIV infection from 10 to 33 days after exposure.
  • Antigen/Antibody tests can detect infection from 18 to 45 days after exposure or 18 to 90 days after exposure .
  • Antibody tests can detect infection 23 to 90 days after exposure.

If the test is negative and you feel youve been exposed, get retested.

Hiv Tests Used In British Columbia

Antibody tests

These tests measure antibodies to HIV. Antibodies are proteins made by the immune system when the body is exposed to an infection. It takes time for the body to make antibodies after it is exposed to HIV, and different people make antibodies at different rates.

The window period for antibody tests is between 3 weeks and 3 months. Up to 95% of people will have antibodies after 6 weeks, and 99% of people will have antibodies after 3 months.

The point-of-care HIV test is an antibody tests offered in some locations in BC. The HIV Confirmatory Assay is an antibody test used to confirm a preliminary positive HIV result.

Antigen tests

The 4th generation Enzyme Immunoassay Test test is a combined antigen / antibody test. The antigen, or viral protein, used to detect HIV is called p24 antigen. This p24 antigen shows up in the blood soon after a person gets HIV.

The 4th generation EIA test is the standard HIV laboratory screening test used in BC. Ninety-nine percent of these tests will be positive 6 weeks after a person gets HIV.


This test looks for the genetic material of HIV in the blood. It is also known as the early HIV test or RNA test. Ninety percent of NAATs are positive 10 to 12 days after a person gets HIV, and over 99% are positive after 6 weeks.

The RNA NAAT can be specially ordered by doctors or nurses if someone has had a recent high-risk exposure to HIV and/or they are having symptoms that are highly indicative of HIV.

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Hiv Testing In A Health Care Setting Or Lab

If you take a test in a health care setting or a lab, a health care provider or lab technician will take a sample of your blood or oral fluid. If itâs a rapid test , you may be able to wait for the results, but if itâs a laboratory test, it can take several days for your results to be available. Your health care provider or counselor may talk with you about your risk factors, answer any questions you might have, and discuss next steps with you, especially if your rapid test result is positive.

  • If the test comes back negative, and you havenât had an exposure during the window period for the test you took, you can be confident you donât have HIV.
  • If your HIV test result is positive, the lab will conduct follow-up testing, usually on the same sample as the first.

What Should I Expect During The Hiv Test

Selecting an HIV Test: A Narrative Review for Clinicians and ...

Your experience will depend on which test you take and where you take it.

Lab HIV tests

Most HIV tests involve a healthcare professional drawing blood and sending it to a lab for analysis. These tests may take place in your providers office or a clinic. If you test positive, your provider will do additional testing to confirm the results. The CDC recommends the following sequence of HIV tests:

  • Test #1: An antigen/antibody test to check for HIV antigen p24 and HIV antibodies. Youll need a second test to confirm the results if you test positive.
  • Test #2: An antibody test to check for antibodies associated with the two types of HIV, HIV-1 and HIV-2. A second positive result will confirm that youre HIV-positive. If the results are inconclusive, youll need to take a third test.
  • Test #3: A NAT test to check for HIV in your blood.

This combination of testing is nearly 100% effective at diagnosing HIV.

Rapid HIV tests

Rapid tests check your blood or oral fluid for HIV antibodies. There is also a rapid HIV antigen/antibody test. A healthcare professional may collect blood using a blood draw from a vein or a finger prick. An oral fluid sample will require a mouth swab.

Some rapid tests can provide results in as little as five minutes. Keep in mind that these results are preliminary. If your result is positive, youll need to follow up with your healthcare provider to take an additional test before youll know your HIV status.

At-home HIV tests

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How Should Prep Use Influence Hiv Test Selection

Data are accumulating that users of tenofovir disoproxil fumarate -based PrEP who become infected in the context of poor adherence may have delayed seroconversion on blood-based and oral POC tests. In the Partners PrEP Study, participants underwent POC testing on whole blood with both IgM/IgG and p24/IgM/IgG sensitive tests and had samples sent for multiple laboratory-based assays every 3 months.19 Delayed seroconversion was defined as > 100 days between the first laboratory-based evidence of infection and the first POC test reactivity for the participant. Compared with those on placebo, participants with any pharmacological evidence of adherence during the seroconversion period had 7.2 times the odds of delayed seroconversion plasma RNA levels were lower, as well but still detectable.19 Among participants randomized to receive single-agent TDF in the Bangkok Tenofovir Study who subsequently became HIV-infected, oral antibody reactivity trailed the first evidence of HIV in blood by a median of 126.5 days.20 Taken together, these findings underscore the importance of using laboratory-based serum or plasma tests whenever possible in the management of PrEP users and having a low threshold for augmenting p24/IgM/IgG sensitive assays with nucleic acid testing among users with known or suspected poor adherence.

What To Expect During A 4th Generation Hiv Test

  • The fourth generation test is done with a small sample of your blood, which will be drawn from your arm using a needle or from a finger stick. This sample is then sent to a lab by your healthcare provider or the clinic where you were tested.
  • Generally, you can expect results in a few days, but depending on the lab, it may take a bit longer.
  • If you receive a positive result, youll get a second test to confirm the result. Once positive results are confirmed, your doctor will review your treatment plan. Its important to let sexual partners know to get tested as well.
  • Talk to a healthcare professional before and after the test to understand the results and any next steps required.

The fourth generation test is reliable and highly accurate.

The reliability of tests depends on:

  • when you get tested
  • which test is used

The test needs to be done after the window period to avoid false negatives. The fourth generation test done with a blood sample from a vein can detect virus from

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What Is The 4th Generation Hiv Test

The fourth generation HIV test, also called an enzyme-linked immunosorbent assay test, is a more complete screening that can identify acute HIV. This is the time when the virus is multiplying rapidly and youre more likely to pass the infection.

In the first few weeks after exposure to HIV, your body produces an antigen known as p24. This protein is only present in people who have acute HIV infection. It triggers your immune system to respond.

The fourth generation tests can identify both HIV-specific antigen p24 and HIV antibodies with a blood sample.

The fourth generation tests require a blood sample thats sent to a lab for testing. Blood testing done by a lab is the most accurate type of test.

There are many products approved for fourth generation testing, including:

  • ADVIA Centaur HIV Ag/Ab Combo Assay
  • Elecsys HIV Combi PT
  • Genscreen ULTRA HIV Ag-Ab
  • VITROS HIV Combo Test

The healthcare clinic or doctors office you visit for an HIV test can tell you more about the exact test they use.

tests that can test for the presence of HIV. HIV testing can be done by drawing blood from a vein, a finger stick, or taking an oral swab of fluid.

Tests can measure antibodies, antigen/antibody , and theres also a nucleic acid test . The NAT test can identify HIV and viral load . It can tell if you have HIV within around 10 to 33 days of exposure.

Older tests like the third generation tests arent reliable until about 3 months after exposure to the virus.

Where Can People Find Free Hiv Testing Locations

Is negative HIV combo test post 35 days of exposure conclusive? – Dr. Ramakrishna Prasad

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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Two Common Hiv Screening Approaches

Here we discuss two different testing approaches for HIV screening.

Screening is done to find the infection although the patient is not symptomatic.

Both approaches are widely used. Which one is used depends on test availability and the timing of sexual contact. Letâs talk about each approach in more detail.

New testing approach

The fourth-generation HIV testfor Ag and Ab is the preferred test for HIV screening and is currently widely used.

What it detects

This test can detect the antibody and antigen at the same time.

When it is preferred

The P 24 antigen can be seen a bit earlier in the disease process, which is why the accuracy of this test is better for early HIV detection than that of an Ab test.

Test interpretation

  • If the test is negative
  • If the fourth-generation test is negative and done after enough time has passed since exposure, no other testing is necessary.
  • If the test is positive
  • If the fourth-generation test is positive, an HIV 1/2 Ab test to confirm positivity is necessary.
  • A confirmatory test will also tell us what type of HIV virus has been detected, which helps with treatment planning.
  • Old testing approach

    This test is more widely available and costs less.

    What it detects

    The test check for HIV Ab 1 and 2

    When it is preferred

    This test is excellent for detecting an existing STD but not for detecting early HIV detection since early on, production of antibodies has not begun, and the test might have been performed during a time when it is not accurate.

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