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Evaluating the Failures of Exposure Notification Apps

The apps were once seen as a pandemic game-changer, but low adoption rates have undermined their efficacy.

November 18, 2021

Covid-19 expos­ure noti­fic­a­tion apps were touted as a tool that could help turn the tide of the pandemic. However, the apps have failed to achieve their full poten­tial in the United States, where they gener­ally have extremely low util­iz­a­tion rates. Now, as digital vaccine creden­tials are being rolled out across the coun­try, there are valu­able lessons to be learned from what happened with noti­fic­a­tion apps regard­ing user privacy and effic­acy.

Expos­ure noti­fic­a­tion apps were supposed to slow the spread of Covid-19 and help communit­ies emerge from lock­downs. Most state apps are built on the Google/Apple plat­form and designed to supple­ment manual contact tracing by util­iz­ing Bluetooth tech­no­logy in cell phones to notify people who may have been exposed to the virus. Users who test posit­ive for Covid-19 input a code into the app so that anonym­ous noti­fic­a­tions can be sent to the devices of those they have been in prox­im­ity to.

By most accounts, these apps over­prom­ised and under­delivered. Their public health bene­fits are directly linked to uptake levels — the more people who use the apps, the greater the poten­tial reduc­tion in Covid-19 cases and hospit­al­iz­a­tions. However, almost a year after their launch, low adop­tion rates continue to under­mine the apps’ effic­acy. For instance, accord­ing to a survey of state health depart­ments, Arizona ended its digital contact tracing program in July after just 1.3 percent of the state’s popu­la­tion installed Covid Watch Arizona, and less than 1 percent of the popu­la­tion in Wyom­ing has down­loaded the state’s Care19 app.

Even in states with higher parti­cip­a­tion rates, the percent­age of people logging posit­ive Covid-19 cases into the apps remains extremely low. New Jersey and New York report that approx­im­ately 28 percent and 36.5 percent of resid­ents have installed their respect­ive expos­ure noti­fic­a­tion apps, yet just 0.25 percent and 1.73 percent of posit­ive cases, respect­ively, were being logged as of late August.

Other coun­tries have not faced the same prob­lems. More than 40 percent of the weekly cases in the U.K. are repor­ted through the govern­ment app, as compared to the approx­im­ately 2 percent of Covid-19 cases logged across the 17 U.S. states and the District of Columbia that parti­cip­ated in a survey.

The poor usage rates in the United States can be attrib­uted to a multi­tude of factors, but two consist­ent themes have emerged: many Amer­ic­ans are concerned about the apps’ privacy protec­tions and are skep­tical of their effic­acy. An online survey from June 2020 found that 71 percent of Amer­ic­ans did not plan on down­load­ing an expos­ure noti­fic­a­tion app, with the primary reason given being concerns about digital privacy. Another poll found that Amer­ic­ans are more worried about digital contact tracing than other forms of public health surveil­lance, includ­ing tradi­tional contact tracing. Mean­while, Cornell Univer­sity research­ers repor­ted that support among Amer­ic­ans for digital contact tracing increases with stronger privacy protec­tions.

If Amer­ic­ans’ concerns about privacy resul­ted in decreased parti­cip­a­tion in the expos­ure noti­fic­a­tion apps, it also under­mined their useful­ness. For example, some front­line work­ers who down­loaded an app and then had direct contact with Covid-19 patients repor­ted being frus­trated that they never received a noti­fic­a­tion through the app. Mean­while, because of low uptake rates, people who tested posit­ive for Covid-19 often felt the need to manu­ally inform recent contacts rather than rely on the apps to notify those they might have exposed.

It is also likely that trust in the state-run expos­ure noti­fic­a­tion apps — and a will­ing­ness to adopt any Covid-19 mitig­a­tion meas­ures — has been impacted by broader partisan debates about the govern­ment’s hand­ling, and the sever­ity or very exist­ence, of the pandemic. Over the last year, disagree­ments about shut­downs, social distan­cing, masks, vaccine mandates, and whether the coun­try should prior­it­ize stop­ping Covid-19 or restart­ing the economy have intens­i­fied. These issues also played an outsize role in shap­ing recent elec­tions. While Amer­ic­ans across both parties have expressed concerns about misin­form­a­tion, polls have shown that the perceived trust­wor­thi­ness of inform­a­tion from both the White House and the media deeply is divided along party lines. In this envir­on­ment, the govern­ment-admin­istered apps face an uphill battle in winning over a skep­tical public.

In addi­tion to polit­ics and privacy and effic­acy concerns, accur­acy issuesnoti­fic­a­tion delaysinad­equate advert­ising, and a lack of coordin­a­tion by the federal regime also likely played a role in depress­ing parti­cip­a­tion rates, along with the fact that 15 percent of adult Amer­ic­ans do not own a smart­phone. Covid fatigue has also set in for many Amer­ic­ans who have had to navig­ate chan­ging advice and judg­ment calls as health profes­sion­als grappled with a new virus, as well as the highs and lows of increased vaccine avail­ab­il­ity, new surges, and vari­ants.

In all, it was an expens­ive exper­i­ment — state govern­ments spent millions of dollars and devoted signi­fic­ant public health resources to devel­op­ing and market­ing the apps, which ulti­mately have played a limited role in arrest­ing the spread of the virus. The situ­ation cautions us to avoid tech­no­lo­gical solu­tions in the context of Covid-19 and beyond. In the event that tech­no­logy does have a role to play, it is import­ant to take the time to prop­erly vet and develop tools that are privacy-protect­ive and effect­ive.

The fail­ures of the expos­ure noti­fic­a­tion apps coun­sel us to be proact­ively privacy-protect­ive and trans­par­ent when it comes to digital vaccine creden­tials, which we exam­ine here. The chal­lenges posed by partisan disagree­ments about Covid-19 and the equity issues raised by reli­ance on digital systems, partic­u­larly for those without smart­phones, also need to be addressed. Finally, to fore­stall the prolonged debates about effic­acy and privacy that have eroded public trust in the expos­ure noti­fic­a­tion apps, it is imper­at­ive that govern­ments prior­it­ize user privacy and ensure user data is secure before they are released.