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How Accurate Are HIV, PCR, DNA Test After 28 Days With Antibody?

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Posted on Tue, 6 Aug 2013
Question: How accurate are hiv pcr dna test after 28 days done with antibody
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Answered by Dr. Michelle Gibson James (26 minutes later)
HI, thanks for using healthcare magic

There are different tests that can be used to detect HIV. The PCR and the ELISA test.
PCR DNA looks for dna evidence of the virus , in other words it looks for the virus itself.
Because it is checking for the actual virus the window period is 2 to 3 weeks.

The window period is the time it takes for a test to definitively determine whether an infection is present or not.

This means that after 4 weeks or 28 days , the PCR would be able to accurately show whether some one is infected with HIV. The result at this time would be correct and the final result.

The other test, most common screening test (because it is cheaper), the ELISA tests detects the presence of anti bodies.

Antibodies are formed in a person when they react to a particular antigen which could a bacteria, virus or fungi. In this case it is the HIV virus.
For this reason the window period of the ELISA is 3 to 6 months because it can take up to this time in some persons for the antibodies to form.

The PCR test is a antigen dna test, it does not look for the antibody but if you did the antibody test , a definitive result would be in 3 to 6 months.

I hope this helps, feel free to ask any other questions
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Follow up: Dr. Michelle Gibson James (28 minutes later)
would you say i was hiv neg ?
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Answered by Dr. Michelle Gibson James (10 hours later)
Hi, yes if the PCR was done at day 28 then you would definitely be HIV negative.

Please feel free to ask anything else
Note: Get personalized answers to your HIV related queries You can choose to talk face to face with your doctor. Book a Video Call now.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Michelle Gibson James

General & Family Physician

Practicing since :2001

Answered : 16808 Questions

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How Accurate Are HIV, PCR, DNA Test After 28 Days With Antibody?

HI, thanks for using healthcare magic

There are different tests that can be used to detect HIV. The PCR and the ELISA test.
PCR DNA looks for dna evidence of the virus , in other words it looks for the virus itself.
Because it is checking for the actual virus the window period is 2 to 3 weeks.

The window period is the time it takes for a test to definitively determine whether an infection is present or not.

This means that after 4 weeks or 28 days , the PCR would be able to accurately show whether some one is infected with HIV. The result at this time would be correct and the final result.

The other test, most common screening test (because it is cheaper), the ELISA tests detects the presence of anti bodies.

Antibodies are formed in a person when they react to a particular antigen which could a bacteria, virus or fungi. In this case it is the HIV virus.
For this reason the window period of the ELISA is 3 to 6 months because it can take up to this time in some persons for the antibodies to form.

The PCR test is a antigen dna test, it does not look for the antibody but if you did the antibody test , a definitive result would be in 3 to 6 months.

I hope this helps, feel free to ask any other questions