Hi Drs

I had a casual encounter 22 days ago (06/06) with a fellow male of unknown status. I’m on PrEP and used a condom (oral aside), but have a high temp and sore throat so Im anxious. Is that irrational?

I took a test 20 days after which was negative. Is that a good sign or too soon to mean anything?

I was told in clinic (private) that theres no need to retest if its 2 weeks after potential exposure, but guidance in the UK says that should be 28 or sometimes 45 days, so Im confused. Would a private place do their test differently to a free clinic where they can be confident in the result earlier? For context it was a DUO Test (HIV I/II Antibodies, p24 antigen)

Does it have anything to do with the antigen part of the test? From my very basic searching I’ve read antigens appear 10 days post exposure, so is it as simple as that test would most likely pick that up after 20 days?

Thank you for taking the time to read this and any info to help my current worried self would be much appreciated

There is little or no chance you have HIV. First, PrEP is highly effective. Second and even more important, it isn't possible to have HIV symptoms and test negative. Fever and other symptoms of ARS are not caused directly by the virus, but by the immune response to it -- which is indicated by antibody. In addition, p24 antigen almost always is also detectable in symptomatic persons. For these reasons, almost certainly your fever and sore throat have another cause. Have you been tested for the common non-sexually transmitted infections like influenza and covid?

It indeed takes 28 days -- and rarely up to 45 days -- after infection for the HIV AgAb (duo, 4th generation) blood tests to become positive, and I'm surprised your clinic isn't recommending additional testing at these intervals. But HIV is not the cause of your fever, and the chance you were infected despite PrEP is extremely low. Perhaps that's why your clinic is reassuring you in such strong terms. But it would make sense to discuss all this with them.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

Thanks again Dr