Twenty one cases of superinfection have been reported in the scientific literature, but transmission has not been fully documented to confirm these cases. How often it might happen, or if the second type of virus might be more resistant to treatment, is not clear.
Some people believe that superinfection might happen when two HIV-positive persons have sex with each other. Others believe that this does not happen. Some people think that the risk for a second infection with HIV is very low. None of these case reports have fully demonstrated that superinfection happens from having sex.
All agree that having sex without condoms is high risk for other sexually transmitted infections (STIs).
There have been very few studies conducted in the past to see if superinfection happens from having sex. Therefore, HIV-positive persons have had to decide about having sex with each other without much evidence about risk. Public health officials have also offered guidance based on little scientific data. It is very important to find out whether superinfection occurs, and if it does, how often. The Positive Partners Study will also try to find out what kinds of factors predict whether superinfection occurs. We could learn a lot from a single proven case of HIV-1 superinfection. It would change what we tell HIV-positive sex partners about having sex with each other. We are planning to enroll as many as 400 participants from the Bay Area.
