Dr. Sax is director of the HIV Program and Division of Infectious Diseases at Brigham and Women's Hospital in Boston.
The most important thing they can do is avoid getting syphilis or hepatitis C. Those two infections can be really nasty. And even though virologic suppression for HIV leads to a nearly uninfectible situation -- people don't get superinfected if they're on treatment already and they're suppressed; that just doesn't happen. And people don't transmit if they're on HIV therapy and suppressed. But they can definitely still catch hepatitis C and syphilis. And I've seen it happen numerous times, and it is not pleasant. You've got to be careful.
I say, "If you're in a monogamous relationship, where your partner is HIV positive and suppressed, and it's a monogamous relationship, then you guys make your decision. You're not going to get HIV, right? But if you're not sure it's a monogamous relationship, either for you or for him, then you've got to be careful, in these times."