I just have one question, why does the CDC recommend a 3 month period for testing from a low or unknown risk exposure to clear you, but 6 months for a known exposure before you are clear? What is the difference? The seroconversion process doesn't care how you were exposed to HIV, so why is there a difference in the waiting period? I sort of understand their reasoning since you have a higher risk if the person had HIV for sure, but with an unknown risk, they could still for sure have it, but you just do not know? Maybe someone could explain it to me or give your thoughts on it.

My understanding is that people who are exposed in the medical feild can take longer to show positive sometimes due to co-infection with HIV. But to be honest, I have read a few diffrent THEROYS on why some take longer than others, but nothing conclusive. Its not a matter of seroconversion, but rather an INDIVIDUAL will sero-convert, and when. maybe some people have repeated exposure, or dont know exactly when they were infected. If they practice high-risk behavior they could have been exposed more than once. Theres no set answer really. But MOST people seroconvert by 3 months. With a DEFINITE risk you would want to be 100% sure, and that would be 6 months.

the cdc guidelines are pretty confusing. a test at 3 months is pretty conclusive for any risk but they want to make sure they do their best in preventing the disease so they suggest testing again at 6 months just in case your a late seroconverter which is not so common.
many health field workers are at risk for a co-infection of hepatits c which can cause someone to seroconvert later.