National HIV Surveillance System (NHSS)

Overview

Human immunodeficiency virus (HIV) surveillance data are used to detect and monitor cases of HIV infection in the United States, evaluate epidemiologic trends, identify unusual cases requiring follow-up, and inform public health efforts to prevent and control the disease. Data collected on people with diagnosed HIV infection include age, sex at birth, gender, race, ethnicity, transmission category, and geographic region.

Coverage

All 50 states, the District of Columbia (D.C.), and 6 U.S. territories (American Samoa, Guam, Northern Mariana Islands, Puerto Rico, Republic of Palau, and U.S. Virgin Islands) report confirmed diagnoses of HIV infection to CDC using a uniform surveillance case definition and case report form. As of April 2008, all reporting areas had implemented confidential, name-based HIV infection reporting and agreed to participate in NHSS. Health, United States presents data only for the 50 states and D.C.

Methodology

The surveillance programs of local, territorial, and state health departments collect information on demographic, transmission risk, and clinical information that also includes routine reporting of laboratory tests for HIV infection, using a standard confidential case report form. This information is then transmitted electronically, without personal identifiers, to NHSS. HIV surveillance includes case report data from the 50 states, D.C., and 6 dependent areas.

Issues Affecting Interpretation

Annual standard evaluation results indicate that the reporting of cases of HIV infection in most areas of the United States is estimated to be at least 85% complete as of December 2018, although the completeness of reporting of cases of HIV infection to state and local health departments differs by geographic region and patient population. For more information, see: Karch DL, Chen M, Tang T. Evaluation of the National Human Immunodeficiency Virus Surveillance System for the 2011 diagnosis year. J Public Health Manag Pract 20(6):598–607. 2014. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4602389/pdf/nihms724842.pdf.

In 2014, the HIV surveillance case definition was updated. Cases diagnosed through 2013 were classified according to the 2008 HIV case definition. Cases diagnosed after 2013 were classified according to the newly updated definition. The 2014 case definition is similar to the 2008 definition except for: a) inclusion of criteria for stage 0; b) inclusion of CD4 lymphocyte testing for stage 3 in children; and c) changes in the cutoffs for CD4 percentage of total lymphocytes used for classification of stages 1 and 2 in people aged 6 years and over. See Sources and Definitions, Human immunodeficiency virus (HIV) disease and Acquired immunodeficiency syndrome (AIDS) for discussion of HIV diagnoses reporting definitions.

References

• National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention. Diagnoses of HIV infection in the United States and dependent areas, 2019. HIV Surveillance Report, vol 32. 2021. Available from http://www.cdc.gov/hiv/library/reports/hiv-surveillance.html.

For more information, see the NCHHSTP website at: https://www.cdc.gov/nchhstp.