When using a condom while having sex with multiple women, what are?
That depends on whether any of them already have HIV. If not, the chance is exactly zero, condom or no condom. HIV is really not something you need to be worried about in most parts of the world. The reason to use condoms is not so much because you need to protect yourself against HIV, but rather because you need to protect yourself against herpes, HPV, gonorrhea, chlamydia, and syphilis, all of which are far more prevalent in the human population and all of which are also far more contagious than HIV.