Washington state is launching a smartphone app designed to let users know if they have been in close proximity to a person who has tested positive for COVID-19.

Under a program known as WA Notify, iPhone users can enable the program in their settings while Android users can download the app from the Google Play store.

Use of the app is voluntary and users can opt out at any time. Several U.S. states, including Virginia, New York and Colorado, are already using the technology.

When activated, WA Notify will use the phone’s bluetooth technology to exchange random codes with other nearby phones without revealing any personal information or the phone’s location. If people test positive for COVID, they can enter a verification code into WA Notify that will anonymously let others users know that they have been in close proximity to someone with a confirmed positive case in the past 14 days. The notified person can then take appropriate action.

The technology, developed jointly by Apple and Google, is able to preserve privacy and works without collecting personal data.

State officials are hoping that the voluntary use of the app will help tamp down the dramatic rise of coronavirus infections Washington has seen over the past several weeks. Gov. Jay Inslee said Monday over 200,000 state residents had already enabled or downloaded the app.

Data models for King, Snohomish and Pierce counties and studies from both Stanford and Oxford universities show that even a small percentage of users in the state opting in can help make a meaningful reduction in infections and deaths. Health Secretary Jonathan Wiesman said that even just 15 percent of usage could help decrease transmission by 11 percent.

State officials also stressed that a recommendation to adopt the technology was received from an oversight committee that included security and civil liberties experts to help combat the understandable worries of the possibility of leaked personal information.

“WA Notify complements the actions Washington residents are already taking, like wearing masks, physical distancing and keeping gatherings small,” Wiesman said. “We’re excited to be joining the states already using this safe and secure technology and encourage all Washingtonians to join the effort.”

Officials view the technology as a compliment to masking, social distancing and contact tracing efforts in fighting COVID. They also stressed with a vaccine just around the corner — the first shipments to the state possibly coming by mid-December — that now is the time for residents to “buckle down and avoid these social interactions with one another.”

“This is not the moment to reduce our efforts,” Inslee said.