It should also be noted that HIV is most likely to be transmitted when a person doesn't even know they have the virus, especially if this person has been recently infected. A new analysis by the U.S. Centers for Disease Control found that a recently infected person was 92% more likely to transmit the virus than someone who had not been infected recently. This is consistent with our knowledge that HIV is most transmissible in the acute phase of infection, when the virus is circulating in the body at its highest levels. The same CDC analysis also found that people who know their status are less likely to transmit the virus, due to behavioural changes that occur once a person is diagnosed.
In summary, people who know they are HIV positive are the least likely to transmit the virus and HIV-positive people with suppressed viral loads cannot transmit the virus.