Which subgroups of people with HIV are most likely to transmit the virus? According to estimates from the Centers for Disease Control and Prevention (CDC), in 2016, 1.1 million people in the United States were living with HIV, and 38,700 people contracted the virus. Researchers deduced that the  1% of the HIV population with an acute, or very recent, undiagnosed infection accounted for an estimated 4% of all new transmissions. The 14% with a chronic, or longer-term, undiagnosed infection accounted for 34% of transmissions. The 23% who were diagnosed but not in medical care for HIV accounted for 43% of transmissions. The 11% who were diagnosed and receiving medical care but had unsuppressed virus accounted for 20% of transmissions. Lastly, the 51% with an un-detectable viral load presumably did not transmit the virus to anyone, as studies show that undetectable HIV is not transmittable.