All states and U.S. territories report demographic, behavioral, clinical, and laboratory data on persons diagnosed with HIV infection to the Centers for Disease Control and Prevention’s (CDC) National HIV Surveillance System (NHSS). These data are used to estimate the number of persons newly diagnosed with HIV infection (regardless of the stage of disease at diagnosis) and the number of people living with a diagnosis of HIV infection. However, because HIV diagnosis can occur at any point during the long latency between infection and symptom development in HIV disease, and depends on HIV testing and reporting practices, these estimates may not reflect new infections.
As an integrated component of the NHSS, HIV incidence surveillance incorporates into routine case surveillance the collection of data on HIV testing and antiretroviral use history and results from the serologic testing algorithm for recent HIV seroconversion (STARHS) in the states and cities that conduct HIV incidence surveillance*. These data are used to generate annual estimates of the number of new HIV infections, including those diagnosed (new HIV infections in the period of interest among persons who had an HIV test during the period and became aware of their infection) and undiagnosed (new HIV infections in the period of interest among persons who were not yet aware of their infection). In contrast to HIV diagnoses (which can occur at any point after HIV infection), HIV incidence (the total number of diagnosed and undiagnosed HIV infections in a single year) reflects the leading edge of HIV transmission, HIV infection trends, and the impact of HIV prevention efforts. Read more