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.
She pointed out that the research on Pennsylvania’s experience with its exposure notification app concluded that it sometimes took days between someone testing positive for COVID-19, and the case investigation interview to mark themselves as testing positive in the app.
“That really defeats the purpose because it’s so slow.”
She explained that the U.S. is a difficult place to implement such a system, because there is no central health care system, and there is a mix of public and private health coverage, making it “uniquely dysfunctional.”
However, she pointed to Germany as a country with a comparable situation that managed to make their app work by having thousands of COVID-19 test providers integrate their data with the app, which “was a fantastic piece of work and permanently improved the public health information infrastructure.”
“They didn’t let a crisis go to waste,” she said.
She said the U.S. should invest in better testing and infrastructure for future pandemics.
Most of the U.S. states that had an app shut them down last year.
But in Delaware, it led health officials to something better.
During their first big surge in January 2022, public health officials had a hard time calling all the contacts of people who tested positive. They realized that people liked using their phones, and probably would like getting text messages more than using an app. So they did contact tracing by texting people links to an online platform.
Public Health Resource Officer Tracey Johnson says “that text messaging piece was a lifesaver.”
She says hopefully there will not be another pandemic soon, but if there is, they’re going to go with text messages.
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