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About the EHE Indicators: Incidence
There are six EHE indicators: HIV incidence, knowledge of HIV status, diagnoses, linkage to HIV medical care, HIV viral suppression, and PrEP coverage.
Each indicator was chosen with specific public health goals in mind and in line with the four key strategies of the initiative: diagnose, prevent, treat and respond. Incidence measures our overarching goal of reducing new infections by 90% by 2030. Diagnoses, and Knowledge of Status are all key to identifying which individuals need to be linked to care, and represent important steps on the HIV Care Continuum. Data have shown that upon diagnosis, immediate linkage to care and treatment results in improved HIV outcomes, so it is important to track how these indicators change over time. Viral Suppression and PrEP use will have the greatest impact on reducing new transmissions if they are scaled up.
Explore HIV indicator data on the AHEAD dashboard.
What Is HIV Incidence?
HIV incidence is the estimated number of new HIV infections within a specific period, whether or not they have been diagnosed. Incidence reflects new cases of HIV transmission and is displayed on AHEAD as an annual (calendar year) estimate.
The EHE incidence goal is to reduce HIV incidence by 90% from the 2017 baseline of 37,000.
It is important to understand the difference between HIV incidence and diagnoses of HIV infection. HIV incidence refers to the estimated number of new HIV infections during a specified period (such as a year), including undiagnosed infections. This is different from the number of persons with newly diagnosed HIV during that period. Some people may have HIV without knowing it, so the year they receive an HIV diagnosis may not be the same year as when they got HIV.
Uses of HIV Incidence Data
HIV incidence estimates are useful at the local, state, and national levels to monitor trends in HIV transmission overall, in key populations, and geographically. Incidence data can be used to assess changes in characteristics of persons most at risk for getting HIV. This information can then be used to inform:
- Policy and program planning to align HIV prevention, testing, and care services with the most affected populations and places.
- Decision-making around funding allocations.
- Evaluation of the impact of HIV prevention programs.
How Are HIV Incidence Estimates Determined?
CDC derives HIV incidence estimates by modeling when each HIV infection occurred by using CD4 cell count data from diagnosed cases, which indicates how long someone has had HIV. HIV incidence estimates are derived by using National HIV Surveillance System (NHSS) data for persons aged ≥13 years at diagnosis.
CD4+ T-lymphocyte (CD4) cells are a type of white blood cell that help to fight infection. HIV harms CD4 cells, and without treatment, HIV reduces the total number of CD4 cells in the body over time. Because these cells are key to fighting infection and keeping us healthy, CD4 counts are used to determine the health of the immune system of a person with HIV, and by extension, the stage of HIV. The three stages of HIV disease are (1) acute HIV infection, (2) chronic HIV infection, and (3) acquired immunodeficiency syndrome (AIDS).
HIV incidence was calculated by using the result of the first CD4 test after initial HIV diagnosis and the CD4 Depletion Model (CD4 model). The first CD4 test results after HIV diagnosis are routinely collected by all jurisdictions as part of NHSS.
Before HIV treatment begins, the CD4 cell count can be used to estimate the time from infection to the date of the CD4 test. The CD4 model was applied to NHSS data to estimate the distribution of delay from infection to diagnosis and then to produce incidence and prevalence estimates of HIV among persons aged 13 years and older. Reporting of the first CD4 test result after HIV diagnosis is a required data element on the HIV case report form; however, completeness of reporting varies among states and local jurisdictions.
HIV incidence among persons aged 13 years and older was obtained via the following:
- Among HIV diagnoses reported by states to the CDC, the date of HIV infection was estimated for each person with a CD4 test by using the CD4 depletion model.
- The distribution of delay (from HIV infection to diagnosis) was used to estimate the annual number of new infections in a given year, which includes diagnosed and undiagnosed infections.
About HIV Incidence Data
Estimates are rounded to the nearest 100 for estimates greater than 1,000 and to the nearest 10 for estimates less than or equal to 1,000 to reflect model uncertainty. Relative standard errors (RSEs) were calculated for estimates of incidence, prevalence, and percentage of persons living with diagnosed HIV infection and were used to determine the reliability of estimates. Estimates with a RSE of <30% meet the standard of reliability and are displayed. Estimates with a RSE of 30%-50% meet a lower standard of reliability and are displayed but should be interpreted with caution. Estimates with a RSE of >50% are statistically unreliable and not displayed.
Estimates should be interpreted with caution for jurisdictions that do not have laws requiring complete reporting of laboratory data or that have incomplete reporting. Areas without laws: Idaho. Areas with incomplete reporting in 2022: New Jersey and Puerto Rico. Areas with a lapse in reporting in 2022: Mississippi and West Virginia.
Please be advised that data on estimated HIV incidence are for years 2017-2022 only. As a result of a recent reduction in force within CDC's Division of HIV Prevention (DHP), the branch responsible for producing national HIV incidence and prevalence estimates was eliminated. Due to this staffing reduction, updated HIV incidence and prevalence data through 2023 are not currently available.
Estimates for years 2020, 2021, and 2022 should be interpreted with caution due to adjustments made to the monthly distribution of reported diagnoses during those years to account for the impact of COVID-19 on HIV testing and diagnosis in the United States.
Data Sources
Ending the HIV Epidemic (EHE) seeks to reduce the number of new HIV infections in the United States by 75 percent by 2025, and then by at least 90 percent by 2030, for an estimated 250,000 total HIV infections averted. AHEAD is paid for by EHE.
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America's HIV Epidemic Analysis Dashboard (AHEAD) - Paid for by Ending the HIV Epidemic.