National HIV Surveillance System (NHSS)

Years Available
1981 to present
Mode of Collection
Surveillance data: active data collection.
The Centers for Disease Control and Prevention (CDC) collects, analyzes, and disseminates surveillance data on HIV infection and AIDS; these data are the nation’s source of timely information on the burden of HIV infection. Health departments report de-identified data to CDC so that information from around the country can be analyzed to determine who is being affected and why HIV surveillance data are used by CDC’s public health partners in other federal agencies, health departments, nonprofit organizations, and academic institutions to help target prevention efforts, plan for services, and develop policy.
Selected Content
Data include information on demographic characteristics (i.e., sex at birth, gender, race/ethnicity, age, and place of diagnosis), transmission category (mode of exposure), initial immune status, and viral load. In addition, HIV case surveillance activities allow jurisdictions to monitor HIV disease progression and utilization of care services through the ongoing collection of data on laboratory test results (viral load and CD4 counts), opportunistic infections and illnesses, and vital status.
Population Covered
All 50 states, the District of Columbia, and 6 US dependent areas (American Samoa, Guam, Northern Mariana Islands, Puerto Rico, Republic of Palau, and the U.S. Virgin Islands) report confirmed diagnoses of HIV infection to CDC.
Using a uniform HIV surveillance case definition and report form, all 50 states, the District of Columbia, and 6 US dependent areas report confirmed diagnoses of HIV infection to CDC. Case reports are sent to CDC after personal identifying information is removed. HIV Surveillance data present diagnosis, death, and prevalence data without statistical adjustments for delays in reporting of cases to CDC. CDC continues to statistically adjust transmission category data by using multiple imputation techniques to account for missing transmission category information in cases reported to CDC.
Response Rates and Sample Size
HIV infection is one of many nationally notifiable diseases defined by the Council of State and Territorial Epidemiologists in collaboration with CDC. State, local, and territorial governments hold the legal authority for public health surveillance. Although reporting of HIV cases to CDC is voluntary, it is essential to the nationwide aggregation and monitoring of the burden of disease. HIV surveillance consists of the reporting of all cases of confirmed HIV infection. Based on annual standard evaluation results, the completeness of reporting of HIV infection, as of December 2018, is estimated to be at least 85% in all but 3 jurisdictions.
Interpretation Issues
Please use caution when interpreting the following: Data on diagnoses of HIV infection. HIV surveillance reports may not be representative of all persons with HIV because not all infected persons have been (1) tested or (2) tested at a time when the infection could be detected and diagnosed. Also, some states offer anonymous HIV testing; the results of anonymous tests are not reported to the confidential, name-based HIV registries of state and local health departments. Therefore, reports of confidential test results may not represent all persons who tested positive for HIV infection. Deaths: Persons are assumed to be alive unless their deaths have been reported to CDC. Death data are based on death of persons with diagnosed HIV infection and of persons ever classified as stage 3 (AIDS), regardless of cause of death. Due to lags in reporting death data, data are preliminary for a calendar year if based on deaths reported to CDC as of end of the following year. Monitoring viral suppression and knowledge of status is dependent upon complete death ascertainment conducted by HIV surveillance programs for reporting to CDC.