HIV CDR Guidance for Health Departments

Cluster detection and response (CDR) identifies communities affected by rapid HIV transmission. Health departments and their partners then aim to address gaps in prevention and care at individual, network, and systems levels. This guidance describes actions that all health departments can take to develop capacity, engage key partners, and successfully implement CDR activities.

Many people contributed to the development of this guidance, including:

  • Staff from CDC, the Health Resources and Services Administration (HRSA), the U.S. Department of Housing and Urban Development (HUD), and National Institutes of Health (NIH)
  • Staff from state and local health departments
  • Members of the HIV CDR community implementation partners panel

CDC continues to work with partners to identify best CDR practices and will update the guidance regularly.

We have many tools to diagnose, treat, and prevent HIV, but sometimes these services don’t reach people who need them most. HIV CDR allows public health professionals to identify and respond to rapid HIV transmission. Responding includes identifying and closing gaps in prevention and care services for affected communities. Because rapid transmission can affect people beyond the identified cluster, responding at the individual, network, and systems levels is important.

Clusters are a sign of rapid transmission

An HIV cluster or outbreak refers to rapid HIV transmission among people in a sexual or drug-using network. This can occur because communities have limited or no access to HIV prevention and care services. Stigma, discrimination, racism, poverty, and other social and structural factors all contribute to limiting access to these services. Health departments, community-based organizations (CBOs), and other partners use CDR to address these service gaps and improve health equity.

Prioritizing response to HIV clusters is important because clusters have very rapid transmission. For example:

  • Transmission rates in molecular clusters average 8-11 times the national rate.
  • Some clusters and outbreaks have had transmission rates more than 30 times the national rate.
  • Rapidly growing clusters contribute disproportionately to future transmission.

People in detected clusters are only part of the network affected by rapid transmission

For CDR activities, “network” refers to the people in an HIV cluster and those with whom they have sex or share drugs, who may or may not have HIV. Some people with HIV can be in the network, even if they weren’t part of the initially detected cluster. People without HIV in the same sexual or drug-using networks are also considered part of the larger network.

Responding to clusters at individual, network, and systems levels

Because the network experiencing rapid transmission extends beyond the detected cluster, health departments should work to understand the network. Health departments can then address gaps in prevention and care at the individual, network, and systems levels. See Cluster Investigation and Response for examples of these activities.