Hello Doctor, I had a few questions lingering on my mind, and I wanted some clarity on them to look at it from a rational perspective. In your previous response to my previous question asked in April, you mentioned that individuals would test positive 99% of the time with a 4th generation HIV duo test at 28 days after exposure. Mine was at 31 days after exposure, negative result. My exposure was receiving oral sex. I don’t plan on retesting because I trust your analysis more than my anxious mind, but I just wanted some clarification. 

My questions are:

1. Does the 99% positive rate at 28 days leave a 1% chance that my negative result at 31 days was a false negative?

2. In your practice, have you seen any cases where an individual tested negative at 28 days but positive at 42 days after exposure?

3. Is it common or rare for an individual not to have detectable antigen and antibodies at 28 days (31 days in my case) after exposure?

4. You stated that there are NO documented cases reported, in the entire history of the HIV pandemic spanning over 30 years, of someone contracting HIV from receiving oral sex (a blowjob). While it's theoretically possible, do you consider this transmission route negligible in practical terms, even if there was some blood mixed with saliva? 

Thank you for your response. I appreciate you clarifying these concerns for me. 

1. Your risk of acquiring HIV from receipt of oral sex is substantially less than one percent. As I said in my original reply well over 99% of persons who acquire HIV will have positive 4th generation tests for HIV within four weeks of their encounter. In addition, however, please remember that most people do not have HIV. The likelihood that a female partner has HIV is less than one percent. Your putting those two facts together your risk of HIV acquisition is far, far less than one percent 

2.  Neither of us on this forum has ever seen or heard of a person who had a negative test at 28 days which went on to become positive. Such cases are quite rare.

3.  This is a repetitive question which has been answered in my two replies above.  The answer is not going to change.

4.  Yes, the risk of acquisition of HIV upon receipt of oral sex remains theoretical and is certainly negligible. This is true, even if the person performing oral sex has HIV and has blood in their mouth, gum, disease, disease, or oral sores. It is just not something to worry about.

I hope this information is helpful and will allow you to put aside any lingering concerns you have about a risk of HIV from the exposure that you described. EWH