I had protected vaginal sex with a CSW. On the 20th day, I got a negative result for 4th Gen Combo Ag/Ab lab blood test. Another negative result for Rapid 4th Gen Alere Combo on the 48th day. Do I need more testing? What is the likelihood after 3 months it will turn positive?
Thank you for your inquiry. From what we gather from the question, you were asking about whether you require additional testing after your 20 day post exposure 4th Gen combo negative result, and following 48th day post exposure result.
First, it is important to note that your diligence in condom use is commendable. HIV incidence is reduced by 80% with the use of condoms during all acts of penetrative vaginal sex. While condoms do not reduce the transmission of HIV to zero, consistent condom usage is one of the primary methods to protect against HIV transmission (1).
The 4th Generation DUO (Combo) test is known to detect the presence of P24 Antigen immediately and up to the first few weeks after infection with very high accuracy. Because this antibody test has a window period of approximately 4-12 weeks, most HIV specialists consider this test to be conclusive at 6 weeks post exposure (2). Because you received a negative test result 48 days (approximately 7 weeks) post-exposure, there is no need to seek further testing.
All the best, AIDS Vancouver Helpline/Online, Cody