What Is The Accuracy Of P24 Test? Had Protected Sex Relationship With Multiple Women. Chances?

Posted on Sun, 27 Nov 2011

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Sun, 27 Nov 2011 Answered on

Sat, 16 Jun 2012 Last reviewed on

Question : hi doctor i want to ask about accuracy of p24 (combo) test it is negative in day 40 from protected sex relation with 3 womens and also i have oral sex ?
i have also negative antibody test in day 39
why i wait to 3 months as i am very very depressed and i want to be comfort

Follow up: Dr. Rohit Batra (4 hours later)

what about my next test is it better to take another p24 combo test or elisa antibody test in day 60?

Answered by Dr. Rohit Batra (18 hours later)

Hi,
Thanks for posting your query!

P24 is an antigen test and usually gets positive within 7 days of unprotected high risk behavior.
If the antibody test is negative at day 40, it can't be a definitive test as the antibodies are not detectable between 3 weeks to 3 months. This happens as the antigens start combining with the antibodies.
A repeat antibody test needs to be carried out at an interval of 3 months after exposure as it's at that time that antibodies get excessive and are detectable.

So I would advise you to wait for 3 months and get an antibody test done. There is no need to get the combo test repeated.

Regards

Dr.Rohit Batra

Above answer was peer-reviewed by : Dr. Aparna Kohli