Hi, Welcome to icliniq.com.
I went through your query and understood your concern. If the test results after 45 days show that RNA (ribonucleic acid) and PCR (polymerase chain reaction) are negative, then it is almost negative. And the fourth generation ELISA (enzyme-linked immunoassay) is a very sensitive test and that is also negative. So there is nothing to worry about. If the test report says less than 66 copies/mL after 28 days, it means that the test will detect only if the viral load is more than 66 copies/mL. In the case of a primary HIV (human immunodeficiency virus) infection, the viral load will be definitely high in multiples of thousands and easily detectable if tested on the 28th day. In case of any doubts, a test on the 90th day would help you get convinced. Since you were in protected intercourse, the transmission is highly unlikely, even if the client was HIV positive. So, I suggest you to repeat these tests on the 90th day for your betterment.
I hope this has helped you. Take care.