About 1.6 million people, more than one-quarter of Washington’s adult population, have activated or downloaded the WA Notify smartphone app that aims to let people know if they may have been exposed to the coronavirus, the state Department of Health (DOH) said this week.

The app is active and is sending notifications to people who may have been exposed, but the state does not have reliable data on how many times the app has been used to alert people or on how many people have been alerted.

Part of that is by design — privacy protections built into the app limit how much information public health officials get — but part of it is because the data the state does have is messy and filled with possible double-counts or inaccuracies, health officials said.

The app, which the state launched in November, uses a phone’s Bluetooth system to detect proximity of other nearby phones. People who test positive for the coronavirus are given a code to enter into the app. The app then anonymously alerts other users who have been within 6 feet of that person.

“Once you enable it, it’s quietly working in the background of your phone, if you don’t hear anything, that is not a sign that anything’s wrong,” said Lacy Fehrenbach, Washington’s deputy health secretary for COVID-19 response. “No news is good news.”

The app is designed to protect users’ privacy, state health officials say, but officials do have access to some high-level, anonymized data.

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The state Department of Health knows how many codes have been sent out to people who tested positive, and they know how many of those codes were then entered into users’ apps. But, the department said, the data they have is not useful.

It doesn’t account for test codes that local health departments send out as they test and learn the system. It doesn’t account for codes sent to landlines, for codes that expire and are reissued or for codes that are entered incorrectly and then reissued.

“We aren’t using or tracking those numbers and we don’t intend to,” Amy Reynolds, a DOH spokesperson, said. “We have no way to determine how many of the situations above may have occurred because WA Notify is privacy preserving and doesn’t associate verification codes with individual cases.”

Reynolds said they’re also not asking local public health departments to track the number of codes they provide.

Public Health – Seattle & King County has sent out 877 codes to people who completed contact tracing interviews since Dec. 2, Kate Cole, an agency spokesperson said, but there are more caveats with that number.

The local public health department is only doing contact tracing on about 60% of the cases in King County. Many of the rest are farmed out to state contact tracing teams, helping in the counties with the most cases. And, in recent weeks, many cases have not been reached by contact tracers. In five of the last seven weeks, there haven’t been enough contact tracers to reach out to every positive case in King County, according to county data.

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Still, Reynolds said they’ve been very pleased with the public’s participation in the app. Modeling from Oxford, Stanford and Google, which helped develop the technology the app uses, indicated that if 15% of the population in King, Pierce and Snohomish counties used the app, it could reduce infections by about 8% and deaths by about 6%.

Because of privacy settings, there’s no way to know where, within Washington, app participants are located, but the state is well beyond that 15% number.

Starbucks recently sent an email to Washington customers encouraging them to download the app.

“Sign up for WA Notify from Washington State today,” the email said. “When you do, your Apple or Android phone can alert you if you may have been exposed to COVID-19.”

Jessica Conradson, a Starbucks spokesperson, said the email was part of their efforts to support local health officials and government leaders in containing the virus.

Reynolds, the DOH spokesperson, said they’ve heard, anecdotally, from local health departments that people at testing centers have said they were getting tested because they received a notification from the app.

“Making verification codes available quickly and efficiently is our focus right now, rather than measuring how many codes are issued or claimed,” Reynolds said.

wa notify app

The app is free, here’s how to download or activate it

On an Android phone, go to the Google Play store, search for “WA Notify” and then download the app.

On an iPhone, go to Settings, scroll down to “Exposure Notifications,” click “Turn On Exposure Notifications,” select United States, select Washington.