​​​​​​​​​​​​​​APHL, Apple, Google and Microsoft collaborate to bring exposure notifications to the public health communityThrough a collaboration with Apple, Google and Microsoft, APHL is helping to bring COVID-19 exposure notifications to the public health community. This effort supports the novel coronavirus response by enabling state and territorial public health agencies to provide COVID-19 exposure notifications to residents who wish to receive them.

How ​Exposure Notification Works

An important way to combat the spread of an infectious disease like COVID-19 is through contact tracing. Public health officials contact, test, treat and advise people who may have been exposed to an affected person to break the chain of disease transmission. Exposure notifications augment that work by using privacy-preserving digital technology to tell someone they may have been exposed to the virus as quickly as possible. 

How APHL Supports Exposure Notificati​​on

By participating in​ Apple and Google's Exposure Notifications System (ENS)​, APHL helps deliver this groundbreaking technology to public health agencies. An essential element of exposure notifications is a unified digital language for communication, known as exposure notification keys. Rather than each state and territorial public health agency bearing the burden of building and hosting its own key server, a national key server, hosted by APHL on the Microsoft Azure Cloud, securely hosts the keys of those affected users. This enables exposure notifications across the US by assuring that users can find out when they may have been exposed by users from other states.

To reduce the effort needed by public health agencies to bring exposure notifications to their jurisdiction, APHL has also made available a multi-tenant verification server running on Google Cloud. As a part of ENS, a verification server is necessary to ensure a user has received a positive test result before uploading their temporary exposure keys to the national key server. Rather than each public health agency standing up its own verification server and deciding on a verification approach, providing one verification server reduces the time and complexity to deploy ENS.

Learn more about how exp​os​ure notification technology ​works and its privacy protections.​

Participating States

States with an exposure notification app on the National Key Server:​​

  • Alabama
  • Alaska
  • Arizona
  • California
  • Colorado
  • District of Columbia
  • Hawaii
  • Louisiana
  • Maryland
  • Massachusetts
  • Minnesota
  • Missouri
  • Nevada
  • New Jersey
  • New Mexico
  • New York
  • Utah
  • Virginia
  • Washington
  • Wisconsin
​​Map of states with an exposure notification app

States piloting an exposure notification app with a limited population on the National Key Server:

  • Oregon

States that have discontinued an exposure notification app:

  • Connecticut
  • ​Delaware
  • Michigan
  • North Carolina
  • North Dakota
  • Pennsylvania
  • Wyoming

Learn More About COVID-19 Exposure Notifications

Exposure Notifications in Use

Exposure Notification Frequently Asked Questions

Exposure Notification Privacy Policy

Exposure Notification Server Configurations

Partner Communications


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