An antibody test in itself is more than 99% accurate after 8 weeks. A combo test really doesn't provide any additional accuracy over the antibody test at 8 weeks, since p24 antigen
has a relatively short and limited window (1-4 weeks). However, combo tests like the Duo are more accurate than antibody tests within this earlier time frame.
The only conclusive result is an antibody test 3 months post exposure.