Yes, but not in the way we generally think of “being contagious.” HIV does not spread in the way a cold or some other types of virus spread, for example, through the air or through casual contact. People with HIV are contagious in that they can transmit the infection through sexual contact and blood transfusion. People with HIV are most contagious early on in the disease–often before they’ve been diagnosed or even show symptoms. Even though they show no symptoms, their blood may contain high amounts of the virus that can be passed on through sexual contact or through blood. After about 6 months, the amount of the virus in an infected person’s blood goes down. However, an infected person is still able to spread the disease to others, and if the disease progresses to AIDS, the virus becomes very contagious.