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03 / 10 / 2023

After three years of around-the-clock tracking of COVID-19 data from...

Contact Tracing

Center for Health Security/NPR State Survey


This chart is officially out of date as more than 30 states across the US have stopped reporting testing positivity or significantly scaled down their testing reports. The CRC data visualizations will remain available for past dates and reports, but will no longer have up to date information on testing positivity and criteria.


Last Survey: May 2021

Concentration of Contact Tracing Staff per State

The Question: How many total staff do States have assigned to do contact tracing?

Proportion of Contact Tracing Staff to Daily New Cases

The Question: How many contact tracers does a state have in comparison to the number of new COVID-19 cases reported every day?

In the same way that hospitals can be overloaded to a point of inefficiency, contact tracing is only a sustainable method of COVID-19 mitigation when the daily new cases are at or below about 10 cases per day for every 100,000 people. For states to the left of the red line, we can expect that contact tracing is an effective method, but for those to the right of the red line, contact tracers are likely overwhelmed. The grey lines are margins that indicate the proportion of contact tracers to cases.

Prioritization of Contact Tracing Efforts for the Next Phase of the Pandemic

The Question: How will each state prioritize contact tracing in this phase of the pandemic, as vaccination levels rise and COVID-19 daily incidence decreases in the US?

Publicly Available Information on the Number of Contact Tracers by State

The Question: Is the number of contact tracing staff in your state/territory posted publicly on a government website?

The number of active contact tracers can be a good indicator of the robustness of contact tracing programs, but few states make this information publicly available.

Publicly Available Information on Contact Tracing & Transmission by State

The Question: Are data related to contact tracing metrics and/or environments where COVID-19 transmission is occurring being posted publicly on a government website?

The data and results gathered from contact tracing can be very useful to both public health decision makers and individuals. These data show how well contact tracing is working and where transmission is occurring most often. This kind of information is more publicly available than the number of active contact tracers in each state but is still only available in 35.7% of states/territories/District of Columbia

Prevalence of Google/Apple Exposure Notification (GAEN) Adoption by States

The Question: Are states using Google/Apple Exposure Notification in addition to traditional manual contact tracing efforts?

Exposure notification, while still new, is another tool that states can adopt to help people take action to quarantine if they have a COVID-19 exposure.

About this page:


Contact tracing is an essential tool of the public health response to COVID-19. Successful contact tracing programs identify contacts of infected cases early, notify close contacts of their exposure quickly, and enable contacts of cases to quarantine safely by providing social support services. This process can help break chains of transmission and reduce the burden of disease in communities, making it safer for everyday activities like attending school and running or visiting a business.

Contact tracing is a resource intensive and complicated undertaking that relies on the effectiveness of other public health interventions, including physical distancing, masking, and timely diagnostic testing, to be successful. In communities with rising or sustained high daily COVID-19 incidence levels, contact tracing can become quickly overwhelmed – tracers simply cannot keep up with the volume. When incidence is below about 10 cases per 100,000 population per day, contact tracing becomes more operationally feasible and can help keep control of community spread, but when incidence rises above that threshold, contact tracing is not the tool to use to control an epidemic. Even so, any amount of contact tracing still reduces transmission and saves lives and should continue to be one primary public health tool to respond to COVID-19.

In April 2020, experts at the Johns Hopkins Center for Health Security estimated that at least 100,000 new contact tracers would be needed across US. The authors called for a national plan and an initiative to provide guidance and resources to state and territorial health departments to scale up and manage contact tracing programs throughout this prolonged public health crisis.

To date, very few national data have been collected on the status and effectiveness of contact tracing programs in each state. These data will allow us to understand how this intervention is working and where additional resources may be needed. The Johns Hopkins COVID-19 Contact Tracing Data Initiative seeks to fill that data gap.


June 3 NPR Report

Johns Hopkins Center for Health Security faculty, Dr. Crystal Watson, and Lucia Mullen have partnered with NPR to collect state data on contact tracing efforts. The May 2021 data collection is the final survey in a series of surveys that ask state and territorial public health departments questions about COVID-19 contact tracing. NPR and Johns Hopkins fielded previous surveys in April, June, July, October, and December of 2020. The resulting data are reported publicly on the Johns Hopkins Coronavirus Resource Center website. NPR also reports on the results of the survey as it is released.

Contact for Questions:

Dr. Crystal Watson, Johns Hopkins Center for Health Security:
Selena Simmons-Duffin, NPR: