How well do contact tracing apps work in alerting us to COVID?


The Pennsylvania app reached about 5-6% of the target population, Delaware reached 13%, and New Jersey reached 11%.

States are also measuring the number of people who tested positive who recorded these results in the app, as well as the number of people alerted from those recorded results and the number of those who called a state contact tracer.

States are considering ways to encourage more people to download and use the apps, such as adding information about vaccine phases and vendors, which Pennsylvania has done. This could prompt more people to download the apps, as many people call the New Jersey Department of Health or go to their website to look for information on vaccines, said Thalia Sirjue, deputy chief of staff for the department. . The Delaware Department of Health is also thinking about it.

Another idea to make apps more effective at preventing transmission of the coronavirus is to automatically send codes to a person who tests positive, so that they can save that result in their app. Right now, whenever someone in Pennsylvania, Delaware, or New Jersey tests positive, a state contact tracer contacts them to give them a code to enter. It becomes a problem when there are so many cases that not all contact tracers can reach them.

Colorado has already made this process automatic. A case study found it made a big difference, said Stephanie Hannon, senior director of product management for exposure notifications at Google, during the NIH webinar earlier this month.

Hannon pointed out that with human contact tracers sending codes for positive tests, Colorado could send about 17 codes per day; with an automatic system, the state sent more than 4,000 codes per day. It also meant that many more people were uploading positive COVID-19 tests to the Colorado app.

“You get incredible results,” Hannon said during the webinar. “The key message is automation.”

This message gets a little more complicated because sending someone a code automatically may not be as effective as a phone call from a human, said Meghna Patel, assistant secretary of health resources and services at the Pennsylvania Department of Health.

“When someone on the phone walks [you] across the stages there was greater compliance, ”Patel said.


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