HIV Network Detection and Response

Network Detection and Response (NDR), previously known as Cluster Detection and Response (CDR), is the Georgia Department of Public Health's (GA DPH) new laboratory and epidemiological approach to help identify communities affected by recent and rapid transmission of HIV. GA DPH previously used the term “cluster” to align with CDC terminology, but began using the term “network” after receiving feedback from the Georgia Cluster Detection and Response Community Advisory Board in 2025 that the term “network” was preferred because it was less stigmatizing compared to the term “cluster.” 

The HIV Epidemiology Unit at GA DPH has been conducting HIV NDR work since 2018, which includes:

  • Molecular network detection: This consists of looking for groups or “networks” of individuals who have very similar strains of HIV virus.
  • Time-space alerts: These are generated when there is a recent increase in diagnoses (“time”) occurring in the same location (“space”).
  • Other types of alerts: Providers, community members, and partner services public health staff may also notice increasing diagnoses and alert the health department about potential networks. Partner services consists of outreach to people newly diagnosed with HIV to assist them with getting connected to HIV services and notifying their partners.
NDR consists of molecular network detection and time-space alerts. It includes alerts from providers, community members, and partner services staff.

Network Detection and Response Aims: Molecular network detection and time-space alerts create an opportunity to identify gaps in HIV prevention and care services that may not be detected through other efforts. These analyses help GA DPH prioritize resources where HIV is spreading quickly, which allows for early intervention to prevent further spread. 

An Overview of Molecular Network Detection

What are molecular networks, transmission networks, and social networks?

Molecular networks are a subset of a larger transmission network, in which other individuals with HIV are either diagnosed but do not have a sequence or are undiagnosed and unaware of their status. Both molecular networks and transmission networks are connected to larger social networks, individuals who share behaviors, but may not have HIV.

Iceberg representing metaphor of how molecular networks are seen (above surface). Transmission networks and social networks are often not seen (below surface)

What can molecular network detection tell us? 

Image with green check marks for 3 items molecular networks can detect and red X's by 3 items it cannot detect.
  • What Molecular Network Detection Can and Cannot Do (Accompanying Text)

    What molecular network detection CAN do:

    • Molecular network detection can help public health practitioners understand where HIV is being transmitted rapidly, which signals that people in the network cannot access needed services. 
    • Molecular HIV networks can help inform where there may be gaps in services, which can advise HIV care and prevention service planning. 
    • Molecular network detection can help us see the larger transmission network to positively impact more people than just those in the detected network.

    What molecular network detection CANNOT do:

    • Molecular network detection cannot determine a direct HIV transmission link between people. 
    • Molecular network detection cannot tell the direction of HIV transmission between network members. 
    • Molecular network detection does not contain information about the person’s genetic makeup. It only contains information on the genetic makeup of the HIV strain.

Where does the molecular information come from? 

  • When a person is diagnosed with HIV and enters care, HIV drug resistance testing is recommended to guide their initial antiretroviral treatment regimen. As part of drug resistance testing, a specimen is sent to the laboratory, which generates a genetic sequence of the HIV virus. This sequence is shared with public health to monitor for networks. HIV data are always stored securely and held strictly confidential.
  • Reporting requirements: Laboratories are required by law (O.C.G.A. § 31-12-2) to report HIV genetic sequences to GA DPH. 

How does GA DPH detect molecular networks?

  • GA DPH uses a web-based bioinformatics tool called Secure HIV-TRACE (HIV TRAnsmission Cluster Engine), which was developed by CDC, University of California-San Diego, and Temple University to detect HIV networks.
  • Each month, the GA DPH HIV Epidemiology Unit examines the molecular data to look for networks that resulted from HIV transmission in the past three years. Epidemiologists examine current networks to see if they are growing and look to see if new networks are appearing. 

How does GA DPH respond to molecular networks?

When responding to networks, public health organizations can implement interventions at the individual, network, and systems level (see figure below).

  • Individual-level interventions include linkage or relinkage to care, partner services, social services (e.g., transportation or housing), and other health care referrals (e.g., behavioral health or dental care).
  • Network-level interventions aim to reach the network of people experiencing rapid HIV transmission to offer preventive services or additional support. This could include expanded testing and PrEP aimed at reaching transmission network members and social network members.
  • Systems-level interventions focus on structural changes that are often related to programs or policies. Examples of interventions could include opt-out emergency department HIV testing, improving transportation or housing services, or tailoring programs to be more culturally competent.
Tailored treatment and prevention interventions occur at the individual, network, and system levels.

An Overview of Time-space Alerts

Alerts occur when there is an increase in HIV diagnoses in the past 12 months compared to the prior 3-year average (“time”) occurring in the same county at diagnosis (“space”). GA DPH then investigates the alert to determine if there is ongoing HIV transmission and to direct intervention efforts. 

When are time-space alerts beneficial to use? 

Time-space alerts are particularly useful for detecting increasing diagnoses among people who inject drugs and in areas with smaller populations or lower rates of HIV.

What are the limitations of time-space alerts? 

Alerts will sometimes identify increases that are a result of increased testing, population growth, or improved access to care, and not necessarily increased HIV transmission. It is important to consider local context, other molecular network detection findings, and overarching diagnosis trends when interpreting alerts. For example, alerts can be affected by the lower number of HIV diagnoses that occurred during the COVID-19 pandemic.

 

Georgia Network Detection and Response Resources & Data

More Information

Case Reporting: For instructions on how to report HIV/AIDS cases and lab reports, see HIV/AIDS Case Reporting.

How To Request Data: To request data beyond what is included on the GA DPH website, please visit PHIP Data Request to create a PHIP data request account and complete the data request form.

Contact Us

Director of Viral Hepatitis, HIV, and STI Epidemiology Section
Dr. Jenna Gettings, DVM, MPH
[email protected]

Page last updated 02/12/2026