New App Can Tell You If You've Been Exposed To Coronavirus, But Only If Enough People Use It

May 18, 2020

Public health officials have cited contact tracing as a key part of lifting lockdowns and continuing to prevent the spread of the coronavirus; a new app developed at Carnegie Mellon University could make the effort easier.

NOVID launched in the Apple app store and Google Play last week. It’s the first app of its kind made in the United States, according to creator and CMU math professor Po-Shen Loh.

NOVID traces users and warns them about exposure risks in their network. If a user tells the app if they’ve tested positive for the virus, people that have come into contact with that user recently will receive a notification. After a user reports positive, their network is only alerted once. Then those users can decide whether or not it’s in their best interest to get tested or go near a relative who could be at higher risk for severe effects of the virus.

Loh said it's all anonymous.

"It doesn't ask you for your phone number, it doesn't ask you for your name. It doesn't even ask you for a username and password," he said. It does require permission to use a device’s Bluetooth and microphone.

NOVID records ultrasonic sounds sent by other phones using the app. That makes it more accurate than Bluetooth alone, according to Loh. Bluetooth and GPS technology could measure signals through walls or floors which could produce false positives for apartment dwellers.

“That person above you … is the closest person to you in this apartment complex, and the Bluetooth signal will go right through that ceiling,” Loh said. “In some apartment buildings, you maybe never even met that person.” The ultrasonic sound, however, won't go through walls and ceilings.

A number of contact tracing apps are in various stages of development, but NOVID is already available in both major app stores. That required a lot of paperwork and references, according to Loh.

“Google and Apple did not want to let just anyone put COVID-19 apps into the app stores,” he said. “We had to get letters of support from the Mayor [Peduto], Allegheny County, even from Allegheny Health Network.”

The more people that download the app, the better it works. But if most of a social circle downloads the app, it’s already useful according to Loh.

“Step one is ‘get everybody to join this platform to help them keep themselves safe and their loved ones safe.’ And step two is to go and use the platform to actually curb the spread of COVID-19 and hopefully bring our society back to something like what it was before,” he said.