Alphabet Inc.’s Google and Apple Inc. announced a new system that will enable public health authorities to use smartphones to assist in contact tracing without having to build an app.

North Dakota, Wyoming and Alabama are the latest U.S. states launching apps to warn users about potential exposure to the novel coronavirus by tracking their encounters, representatives for the states told Reuters.

Virginia launched the first contact tracing app for the novel coronavirus in the United States that uses new technology from Apple Inc. and Alphabet Inc.’s Google.