COVID exposure apps: Did they help curb spread? – WHYY

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In 2020, people wanted a way to tell if they might have been exposed to COVID-19.

More than 20 states in the U.S., including Pennsylvania and Delaware, used a smartphone app that applied existing bluetooth technology to keep track of how far away someone was from another person who had the app. It also sent out alerts if those people later reported themselves as having COVID-19. Each state had their own version of the app.

In the U.S. people were not required to use these apps, and few did, making them less effective than in other countries. But experts say public health authorities in the U.S. can still learn from the experience and be more prepared the next time a pandemic happens.

The Association of Public Health Laboratories managed the exposure notification program for states in the U.S. that used an app to warn people about exposure to COVID-19. Senior consultant Emma Sudduth said they were excited about this in the beginning.

Every time a friend or family in another state received an exposure notification, I was always told, and I was always very proud to hear that they had gotten a notification that they were delaying their trip to visit their grandma, that they were going to start testing, that they were monitoring.

She said the association estimates that around 10% of the entire U.S. population, millions of people, downloaded an exposure notification app. But this was not enough for these apps to be broadly effective.

We were building the plane while we were flying it, so to speak, Sudduth said.

Earlier this year, researchers at the Centers for Disease Control and Prevention worked with Pennsylvania health officials to study how much of a difference the app made in Pennsylvania. They found that from the end of 2020 to the start of 2021, around 5% of the people they surveyed had downloaded the app. Of the people who tested positive for COVID-19 in their survey, only 0.2% of people had installed the app.The researchers concluded this limited how effective the app could have been.

Joanna Masel, an evolutionary biologist at the University of Arizona, helped develop an app for her university, and the state of Arizona. She said it helped reduce transmission on campus by making a real but modest impact.

She added that exposure notification apps will probably be effective in the U.S. in places like that smaller, tightly connected communities like workplaces, colleges, and schools, where people can also be more consistently and quickly tested.

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COVID exposure apps: Did they help curb spread? - WHYY