Estimated HIV Incidence and Prevalence in the United States, 2017–2021: Commentary

The primary goal of the Ending the HIV Epidemic in the U.S. (EHE) initiative is to reduce the annual number of new HIV infections by 75% by 2025 and by at least 90% by 2030 [1]. A key objective to reaching this goal is to increase the percentage of persons with HIV who have received an HIV diagnosis and are aware of their infection, also referred to as knowledge of status [1]. Persons who are aware of their HIV infection can be linked to care and receive HIV treatment to achieve sustained viral suppression, which can reduce morbidity and mortality and prevent HIV transmission to HIV-negative partners through sex [2]. Estimates of (1) HIV incidence, (2) prevalence (persons living with diagnosed or undiagnosed HIV infection), and (3) percentage of diagnosed infections among persons living with HIV (knowledge of status) are essential to determining whether prevention program efforts are reducing the annual number of new HIV infections (incidence) and achieving prevention outcomes.

Incidence measures the number of infections during a specified time (e.g., year). These estimates can be used to assess changes in characteristics of persons with newly acquired HIV infection. Diagnoses refer to persons who may have been infected years before diagnosis.

Prevalence refers to the number of persons living with HIV disease at a given time regardless of the time of infection or whether the person has received a diagnosis. Prevalence and the percentage of diagnosed infections among persons living with HIV reflect the number of persons in need of care and treatment services for HIV infection.

To produce the HIV incidence and prevalence estimates in this report, we used the result of the first CD4+ T-lymphocyte (CD4) test after HIV diagnosis and an estimation method based on a CD4 depletion model (referred to hereafter as the “CD4 model”) [3–6]. The first CD4 test results after HIV diagnosis are routinely collected by all jurisdictions as part of the National HIV Surveillance System (NHSS). See Technical Notes for additional information.

Report Changes

• This report is presented in a new, digital format that includes figures based on charts and maps from the “Estimated HIV Incidence and Prevalence in the United States” slide set.
• The monthly distribution of diagnoses reported to the Centers for Disease Control and Prevention (CDC) during 2020 and 2021 were adjusted to account for the impact of COVID-19 on HIV testing and diagnosis in the United States [7–13]. Estimates for years 2020 and 2021 should be interpreted with caution. See Technical Notes for additional information.
• A Special Focus Profiles section is included to highlight 3 key populations: (1) Gay, Bisexual, and Other Men Who Have Sex with Men (MSM), (2) Persons Who Inject Drugs (PWID), and (3) Persons Aged 13–24 Years.

Impact of COVID-19 Pandemic

Data for the year 2020 should be interpreted with caution due to the negative impact of the COVID-19 pandemic on access to HIV testing, care-related services, and case surveillance activities in state/local jurisdictions. The overall number of HIV diagnoses in the United States in 2020 (30,335) was 17% lower than in 2019. The decline in 2020 was larger than the average yearly decline (2%–3%) observed during 2017–2019 [8]. The underdiagnosis of HIV in 2020 was likely due to disruptions in HIV testing and clinical care services, patient hesitancy in accessing clinical services, and shortages in HIV testing reagents/materials [9–13]. To emphasize the need for caution, tables presenting data for the year 2020 include “COVID-19 pandemic” in the title, and the 2020 column is highlighted in tables that provide multiple years of data. Assessments of trends in HIV diagnoses, deaths, and prevalence that include data for the year 2020 should be interpreted with caution.

During 2021, the overall number of HIV diagnoses in the United States (35,769) partially rebounded and was 18% higher than in 2020 [14]. The partial rebound in the number of HIV diagnoses may be due to the identification and reporting of HIV cases missed in 2020. The ongoing impact of the pandemic on HIV testing, diagnoses, and treatment has varied by jurisdiction, with some recovering more slowly than others. In 2021, some jurisdictions’ levels of HIV testing, diagnoses, and treatment remained below pre-COVID–19 levels [15]. Increasing testing efforts and innovative strategies to reach persons with undiagnosed HIV are needed to offset this diagnosis gap. Assessments of trends in estimated HIV incidence and prevalence that include data for the year 2020 should be interpreted with caution.