National HIV Surveillance System (NHSS)

At a glance

The National HIV Surveillance System (NHSS) is the primary source of HIV data for monitoring cases of HIV infection in the United States and 6 U.S. territories and freely associated states (American Samoa, Guam, Northern Mariana Islands, Puerto Rico, Republic of Palau, U.S. Virgin Islands). The data are reported by laboratory and health care providers to state or local surveillance programs, who in turn report the data to CDC.

This is an image showing various data elements displayed from a computer screen, representing HIV surveillance data.

How NHSS data are collected

Surveillance programs of local, territorial, and state health departments gather information on demographic characteristics (sex assigned at birth, gender, race/ethnicity, age, and place of diagnosis), transmission category (mode of exposure), and all test results indicative of HIV infection and for monitoring stage of disease (viral load and CD4 count and percent).

Information collected includes routine reporting of laboratory tests for HIV to the health department using a standard confidential case report form or via direct reporting from the laboratory. This information is then transmitted electronically, without personal identifiers, to CDC as part of the NHSS.

How NHSS data are used

Data are used to

  • monitor the distribution and transmission of HIV,
  • plan and evaluate prevention and care programs,
  • allocate resources,
  • inform policy development, and
  • identify and respond to rapid transmission of HIV.