Data for the years 2021 & 2022 are preliminary. Due to the impact of the COVID-19 pandemic, data for the year 2020 should be interpreted with caution. Visit for the latest Coronavirus Disease (COVID-19) updates.
COVID-19 disruptions in HIV, diagnosis, care and reporting of deaths during 2020 have also made incidence, prevalence, and knowledge of status estimates derived from a CD4-based model, unreliable. Therefore, the HIV surveillance supplemental report Estimated HIV Incidence and Prevalence in the U.S., which provides data on estimated incidence, prevalence, and knowledge of status in the U.S., was not published by CDC this year.

Transmission Category | AHEAD


Learn more about the terminology used in the Ending the HIV Epidemic: A Plan for America initiative.

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Transmission Category

This is the term for the classification of cases that summarizes a person’s possible HIV risk factors; the summary classification results from selecting, from the presumed hierarchical order of probability, the one risk factor most likely to have resulted in HIV transmission. The exception is men who had sexual contact with other men and injected drugs; this group makes up a separate transmission category.

Transmission category data have been statistically adjusted to account for missing transmission category; therefore, values may not sum to column total.

Transmission category is classified based on a hierarchy of the risk factors most likely responsible for HIV transmission; classification is determined based on the person’s sex assigned at birth.

Persons whose transmission category is classified as male-to-male sexual contact include men who report sexual contact with other men (i.e., homosexual contact) and men who report sexual contact with both men and women (i.e., bisexual contact).

Persons whose transmission category is classified as injection drug use (IDU) are persons who injected non-prescribed drugs.

Heterosexual contact includes persons who have ever had sexual contact with a person known to have, or with a risk factor for, HIV infection.

Other category includes other risk factors including, hemophilia, blood transfusion, perinatal exposure, and risk factor not reported or not identified.