- Have lived with the infection for 10 to 15 years and remained healthy.
- Do not have declining CD4+ cell counts.
- Have a very low level of HIV in their blood.
A small number of people never become infected with HIV despite years of exposure to the virus. For example, they may have repeated, unprotected sex with an infected person. These people are said to be HIV-resistant. These people are never infected, so they can't spread HIV.
Studies are under way to determine why some people either don't become infected with HIV or, if they do, why they don't develop symptoms or lose CD4+ cells. Research has shown that:
- Some people's CD4+ cells are relatively resistant to HIV. If HIV cannot attach itself to CD4+ cells, it cannot destroy them.
- Some people's immune systems may be better able to destroy the virus.
- Some strains of HIV may not be as harmful.