Maybe the other routes simply weren't tested for. Sex is how most people get HIV, so it makes sense to start from here. The second most common is by sharing nee

Maybe the other routes simply weren't tested for. Sex is how most people get HIV, so it makes sense to start from here. The second most common is by sharing needles, usually by drug addicts, and I can't think of an ethical way of doing a trial in such conditions. The rest is mother-child transmission, which is irrelevant as the drug is not intended for fetuses, and the odd accident which is probably too uncommon to make meaningful statistics.