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Dr Uzair
Dr Uzair, Doctor
Category: Medical
Satisfied Customers: 7349
Experience:  MBBS, FCPS (R) General Surgery. Years of experience in Emergency Medicine.
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How accurate is a combo hiv test antigen and

Resolved Question:

How accurate is a combo hiv test for p24 antigen and antibody at 18 days post exposure. I had a test that came back negative. Although the official guidline from the nhs is 4 weeks post exposure, however quite a lot of stuff on the internet said in a lot of positive cases the antigen would show up early. I realise this is not completely conclusive but wanted to ask how reasuring it is and how accurate at this stage?
Submitted: 1 year ago.
Category: Medical
Expert:  Dr Uzair replied 1 year ago.
Hi and thanks for the query,There is probability of false negative at 18 weeks so you have to wait till 4 weeks. It is too early to comment at this stage, it can go either way but there are 70 to 80 percent chances that you are negative for HIV. but test at 4 weeks would be conclusive.Please do leave a positive rating.Best.
Customer: replied 1 year ago.
ok but just to be clear in majority of cases of hiv positive people would it show up at 18 days? I understand that a lot of people in this scenario would not have antibodies produced in response to the virus until 28 days but the antigen p24 is normally produced from 10 days. since the test looks for both would the antigen not be likely to show up at this stage?
Expert:  Dr Uzair replied 1 year ago.
Usually antigen show up from 10 to 15 days but at times it can take longer so we can not say anything with certainity at this stage but a negative test can reassure you a bit.Please do not forget to leave a positive rating.Best.
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