HIV Test after 9 days : which test to do

Published Date : 2023-09-08T20:54:05.696Z

Updated Date : 2023-09-08T20:54:05.696+00:00

How does the HIV virus multiply inside the body

Following exposure to the HIV virus, the virus initiates its replication cycle within submucosal cells. Upon meeting CD4 helper T cells, pivotal players in the immune system, the virus establishes contact. The virus's genetic material, manifested as viral RNA, infiltrates these CD4 cells. Through the action of reverse transcriptase, the viral RNA undergoes conversion into viral DNA. This viral DNA then orchestrates the cell's machinery to manufacture a higher volume of viral particles. Eventually, the infected cell's capacity is exceeded, causing it to rupture and release the generated virions into the bloodstream.

What viral particles are in the body around 9 days after exposure?

At 9 the viral RNA may be detectable, since RNA multiplication is already evident at this stage.

The HIV Virus comprises of four detectable markers : HIV RNA, HIV P24 antigen, HIV IGM Antibodies and HIV IGG ANTIBODIES

What is a window period?

In the context of HIV infection, the window period is the stage when testing might yield ambiguous or false-negative results due to the virus not being fully established in the body.

Which are the different tests that can be done to detect HIV?

Testing for HIV involves diverse methods that seek out various components of the virus. These methods include tests that pinpoint the p24 antigen, antibodies like IgM and IgG, and the utilization of RNA PCR for enhanced sensitivity.

Third Generation Tests

3rd generation tests are so called because they detect antibodies to the HIV 1 and HIV 2 strains. These tests are available in two formats - lab based automated assays, which automate the processes of pipetting and dispensing and point of care assays that can be done using standard manual pipetting.

Fourth Generation Tests

4th generation tests are so called because they detect both the HIV P24 antigen as well as antibodies to the HIV 1 and HIV 2 strains. These tests are available in two formats - lab based automated assays, which automate the processes of pipetting and dispensing and point of care assays that can be done using standard manual pipetting.

Will a 4th generation lab based test detect HIV at 9 days?

There is a low chance of a 4th generation lab based test being able to detect the virus in your body on day 9 after exposure to the HIV virus. This is because the analytes measured by this test, namely - p24 antigen, IgM and IgG antibodies are not yet present in adequate concentration in your blood by day 9 of the infection.

The 4th generation HIV test is a sophisticated screening method that combines the detection of the p24 antigen and IgM/IgG antibodies in a single test, advancing diagnostic capabilities..Lab based assays as described above are fully automated and are considered to be one of the most sensitive tests for early diagnosis of HIV. If you were exposed to HIV, there is a 20.9% chance that the 4th generation lab based assay will be able to detect the virus at 9 days. This is based on the varying levels of the p24 antigen as well as the time it takes for the antibodies to develop in the body agains the virus. It is recommended that you retest after some days since the chances of detecting HIV increase with time.

Will a 4th generation Point of Care based test detect HIV at 9 days?

There is a low chance of a 4th generation point of care based test being able to detect the virus in your body on day 9 after exposure to the HIV virus. This is because the analytes measured by this test, namely - IgM and IgG antibodies are not yet present in adequate concentration in your blood by day 9 of the infection.

.Point of care assays as described above are generally performed with methods like lateral flow immunochromatography and are well suited for low resource and bedside settings. These assays have now achieved comparable results to lab based assays. If you were exposed to HIV, there is a 20.3% chance that a 4th generation point of care based assay will be able to detect the virus at 9. This is based on the varying levels of the p24 antigen as well as the time it takes for the antibodies to develop in the body agains the virus. It is recommended that you retest after some days since the chances of detecting HIV increase with time.

Will a third generation lab based assay detect HIV at 9 days?

There is a low chance of a 3rd generation lab based test being able to detect the virus in your body on day 9 after exposure to the HIV virus. This is because the analytes measured by this test, namely - IgM and IgG antibodies are not yet present in adequate concentration in your blood by day 9 of the infection.

The 3rd generation HIV test is a conventional method that detects both IgM and IgG antibodies against the virus, contributing to early diagnosis..Third generation assay only test for the IgM and IgG antibodies, as such the latency for positivity with these assays is greater. Third generation lab based assays use automation in various steps of the test and as such are considered to be more accurate than the point of care tests, however they require more expensive equipment. If you were exposed to HIV, there is a 18.8% chance that a 3rd generation lab based assay will be able to detect the virus at 9 days. This is based on the time it takes for the antibodies to develop in the body agains the virus. It is recommended that you retest after some days since the chances of detecting HIV increase with time.

Will a third generation point of care based assay detect HIV at 9 days?

There is a low chance of a 3rd generation point of care based test being able to detect the virus in your body on day 9 after exposure to the HIV virus. This is because the analytes measured by this test, namely - IgM and IgG antibodies are not yet present in adequate concentration in your blood by day 9 of the infection.

.Third generation assay only test for the IgM and IgG antibodies, as such the latency for positivity with these assays is greater. Third generation point of care based assays use lateral flow chromatography or similar techniques and are suited for low resource settings. If you were exposed to HIV, there is a 15.0% chance, that a 3rd generation point of care based assay will be able to detect the virus at 9 days. This is based on the time it takes for the antibodies to develop in the body agains the virus. It is recommended that you retest after some days since the chances of detecting HIV increase with time.

Will a RNA PCR test detect HIV at 9 days?

There is a moderate chance of a RNA PCR Molecular Test being able to detect the virus in your body on day 9 after exposure to the HIV virus. This is because the analytes measured by this test, namely - HIV Viral RNA are not yet present in adequate concentration in your blood by day 9 of the infection.

RNA PCR assays can detect viral loads as low as 20 copies of viral RNA/ml. RNA PCR assays can detect the virus as early as 10-12 days, and almost all patients will show positivity between 20-30 days.Based on the fact that you have been exposed 9 days ago, there is a 37.4% chance of the RNA PCR test being able to detect the virus.You should retest after some days, for confirmation.

What is the confirmatory test for HIV at 9?

There is no 100% confirmatory test for HIV. Any negative test is recommended to be repeated after 45-90 days. Positive tests are usually reconfirmed on repeated sampling in accordance with the guidelines of your country's health organizations. While the RNA PCR test usually has the highest chance of detecting the virus, it is never recommended as a first line test, owing to its cost and complexity. A first line screening test is usually done (4th generation) and if it is positive, additional testing is recommeded.

References

• Hurt CB, Nelson JAE, Hightow-Weidman LB, Miller WC. Selecting an HIV Test: A Narrative Review for Clinicians and Researchers. Sex Transm Dis. 2017 Dec;44(12):739-746. doi: 10.1097/OLQ.0000000000000719. PMID: 29140890; PMCID: PMC5718364.Hurt et,al
• Kevin P. Delaney and others, Time Until Emergence of HIV Test Reactivity Following Infection With HIV-1: Implications for Interpreting Test Results and Retesting After Exposure, Clinical Infectious Diseases, Volume 64, Issue 1, 1 January 2017, Pages 53–59,Delaney et.al