Public health agencies from Germany to the states of Alabama and South Carolina have been waiting to use the Apple-Google
model, while other governments have said the tech giants' privacy restrictions will be a hindrance because public health workers will have no access to the data.
said they're not trying to replace contact tracing, a pillar of infection control that involves trained public health workers reaching out to people who may have been exposed to an infected person. But they said their automatic exposure notification system can augment that process and slow the spread of COVID-19 by virus carriers who are interacting with strangers and aren't yet showing symptoms.
The identity of app users will be protected by encryption and anonymous identifier beacons that change frequently.
User adoption is key to success and we believe that these strong privacy protections are also the best way to encourage use of these apps, the companies
said in a joint statement Wednesday.
The statement Wednesday also included remarks from state officials in North Dakota, Alabama and South Carolina signaling that they plan to use it.
"We invite other states to join us in leveraging smartphone technologies to strengthen existing contact tracing efforts, which are critical to getting communities and economies back up and running, said North Dakota Gov. Doug Burgum, a Republican.
North Dakota had already launched a location-tracking app that about 4% of state residents are using, higher than other U.S. states with similar apps but falling far short of the participation rate that experts say is needed to make such technology useful.
Tim Brookins, the CEO of ProudCrowd, a startup that developed North Dakota's app, said Wednesday that North Dakotans will now be asked to download two complementary apps his model, to help public health workers track where COVID-19 patients have been, and the Apple-Google model, to privately notify people who might have been exposed to the virus.