Impact of Nudges on Downloads of COVID-19 Exposure Notification Smartphone Apps: A Randomized Trial

The Interactive Effect of Social Norm and Self (vs. Others) Benefit Nudges on Downloads of COVID-19 Exposure Notification Smartphone Apps: A Randomized Trial

Eligible participants who were active beneficiaries of a large insurer living in Pennsylvania were sent an email encouraging them to download the contact tracing app in Pennsylvania, COVID Alert PA. Participants will be randomly assigned to one of four conditions in a 2 (Self-benefit vs. Other-Benefit) x 2 (Social Norms Present vs. Social Norms absent) design. All participants received an email that said : "COVID Alert PA is the official Exposure Notification App from the Pennsylvania Department of Health. Join Penn Medicine in the fight against COVID-19 and download COVID Alert PA today!" ---Investigators manipulated the content here--- "The app uses Bluetooth to sense when one person is in close contact with another person with the app. If someone tests positive for COVID-19, and they decide to upload the information to the health department, people who have the app and who have been in contact with them will be alerted. If you are interested in downloading the app, please click COVID Alert PA. We appreciate you joining our efforts. Together we can beat COVID-19!" In the Other-Benefit condition, it said: "It can help you reduce your risk of unknowingly spreading the virus to your friends, family, and larger community." In the Self-Benefit condition, it said: "It can help you determine where and when to get testing, and how to get care if you need it." In the Social Norms Present condition, it said: "Over 650,000 Pennsylvanians have already downloaded the app!" In the Social Norms Absent condition, it said the statement about social norms above. Participants who do not open the initial email received a follow-up email.

This is a 2 (Self-Benefit vs. Other-Benefit) x 2 (Social Norm vs. No Social Norm) design. There are thus four conditions total.

Participants were unaware they were participating in a study, and were thus blinded to their treatment assignment.

As part of their email, they read, "It can help you determine where and when to get testing, and how to get care if you need it." and "Over 650,000 Pennsylvanians have already downloaded the app!"

As part of their email, they read, "It can help you determine where and when to get testing, and how to get care if you need it." They did not read any information about the number of Pennsylvanians who downloaded the app.

As part of their email, they read, "It can help you reduce your risk of unknowingly spreading the virus to your friends, family, and larger community." and "Over 650,000 Pennsylvanians have already downloaded the app!"

As part of their email, they read, "It can help you reduce your risk of unknowingly spreading the virus to your friends, family, and larger community." They did not read any information about the number of Pennsylvanians who downloaded the app.

As part of their email, they will read, "It can help you determine where and when to get testing, and how to get care if you need it." and "Over 650,000 Pennsylvanians have already downloaded the app!"

As part of their email, they will read, "It can help you determine where and when to get testing, and how to get care if you need it." They will not read any information about the number of Pennsylvanians who downloaded the app.

As part of their email, they will read, "It can help you reduce your risk of unknowingly spreading the virus to your friends, family, and larger community." and "Over 650,000 Pennsylvanians have already downloaded the app!"

As part of their email, they will read, "It can help you reduce your risk of unknowingly spreading the virus to your friends, family, and larger community." They will not read any information about the number of Pennsylvanians who downloaded the app.

The investigators measured choice to click on the link to download the COVID Alert PA app or not, conditional on opening the email. Because participants may not immediately open their e-mail, or may return to the e-mail to click the link, we allowed for a period of approximately 7 weeks or 48 days from date of initial e-mail for completion of outcome measure.

Inclusion Criteria: Eligible participants were active beneficiaries of a large insurer living in Pennsylvania. Exclusion Criteria: Participants who did not subscribe to offers and promotions emails were excluded, as were Medigap beneficiaries.