It's a problem that was "solved" long before that by just wearing a condom and protecting yourself against other diseases too, and even pregnancy. Condoms are cheap, widely available and decades of condom-related education has been given out to many different generation of kids and adults worldwide.

Somehow we still need day after pills, abortions, antibiotics and other STD meds, and vaccines, now (hopefully) for HIV too.

And they suck. Everyone who's ever worn one knows they suck. If they're too big they completely kill all sensation, if they're too small they cut off circulation, leading to, you guessed it, total loss of sensation. Topped off with the fact that they fail during higher friction activities (you know, exactly the kind that drastically increase HIV transmission risk), they're never going to be an adequate solution, because there will always be people who'll risk it, because what's the point in having sex if you're not going to feel it anyway?

> Somehow we still need...

So, clearly condoms are not the complete answer. Any solution that does not acknowledge the reality of how people actually behave is going to be imperfect.

We live in a messy world.

If only Isaac Asimov had worn a condom, he might still be with us today.