An analysis of the usage of COVID-19 contact tracing apps in 25 US states and DC finds that only 13 have enough usage to benefit from exposure notification
A year ago, engineers built apps to track potential virus exposure. Our research shows the impact has been mixed—but there's still potential. Tweets: @techreview , @pathcheck_fnd , @charlesmok , @fabiochiusi , @techreview , @techreview , @jennydove , and @techreview Tweets: @techreview : Many of the country's exposure notification apps are underutilized, misunderstood, and not well-trusted—and yet this technology may yet come into its own as a public health tool for future disease outbreaks. https://www.technologyreview.com/ ... @pathcheck_fnd : PathCheck Exposure Notification solutions ranked highly in adoption and user ratings. PathCheck is live in Minnesota, Alabama, Louisiana, Hawaii, Guam, Cyprus and Barbados. Plus the open source code is used by many organizations on campuses and states. https://www.technologyreview.com/ ... https://twitter.com/... @charlesmok : We investigated whether digital contact tracing actually worked in the US A year ago, engineers built apps to track potential virus exposure. Our research shows the impact has been mixed—but there's still potential. https://www.technologyreview.com/ ... Fabio Chiusi / @fabiochiusi : “Even after our analysis, it's still hard to answer that crucial question: how many infections were actually prevented by exposure notifications?” https://twitter.com/... @techreview : We reached out to every state public health department that launched a digital contact tracing system and examined app reviews left by anonymous Americans. Our investigation shows the impact has been mixed—but there's still potential. https://www.technologyreview.com/ ... @techreview : Many of the country's exposure notification apps are underutilized, misunderstood, and not well-trusted—and yet this technology may yet come into its own as a public health tool for future disease outbreaks. https://www.technologyreview.com/ ... Jenny Wanger / @jennydove : For the first time ever - usage data by state for #exposureNotification, and some other great insights into EN apps across the US. @betsyladyzhets did some serious digging to make this happen. via @techreview https://www.technologyreview.com/ ... @techreview : A year ago, engineers built apps to track potential virus exposure. Our investigation shows the impact has been mixed—but there's still potential. Thread 🦠📱 https://www.technologyreview.com/ ...
Context & Ripple Effects
State-led contact-tracing efforts were already struggling to gain users in mid-2020, when many states retreated from app plans and early launches struggled with adoption. By November, 14 states and DC had released apps, but coverage described uptake as uneven amid COVID-19 politicization.
The underlying distribution layer arrived when Apple and Google opened their Exposure Notification API to public-health apps. The new analysis shows that technical availability and state-by-state release did not by themselves create enough participation for the service to be useful.
First-order effects
- The 13 jurisdictions with insufficient usage cannot obtain the intended exposure-notification benefit from their existing apps, while the 13 that clear the threshold become the meaningful operating cohort in the study.
- State public-health agencies must treat participation, understanding, and trust as operational constraints rather than assuming an app launch creates a functioning notification network.
Second-order effects
- Apple and Google's API remains a deployment enabler, but state programs are pushed to compete on adoption and public confidence after uneven uptake across the first wave of state releases.
- Privacy concerns become a practical performance issue: the related coverage of surveillance fears around India's high-download tracing app illustrates why download totals alone are not a sufficient measure of durable public-health utility.
Third-order effects
- Digital public-health systems are likely to be evaluated as trust-dependent networks, where privacy governance and participation determine whether a technically interoperable service produces population-level value.
- If this pattern persists across future outbreaks, governments will face pressure to build adoption and legitimacy into emergency-tech programs before deployment rather than treating them as post-launch communications problems.
The trend: Exposure notification is becoming a test of whether public-health technology can convert smartphone reach into trusted, sufficiently dense participation.