App Use and Usability of a Barcode-Based Digital Platform to Augment COVID-19 Contact Tracing: Postpilot Survey and Paradata Analysis

Abstract

Background: The COVID-19 pandemic has drastically changed life in the United States, as the country has recorded over 23 million cases and 383,000 deaths to date. In the leadup to widespread vaccine deployment, testing and surveillance are critical for detecting and stopping possible routes of transmission. Contact tracing has become an important surveillance measure to control COVID-19 in the United States, and mobile health interventions have found increased prominence in this space.

Objective: The aim of this study was to investigate the use and usability of MyCOVIDKey, a mobile-based web app to assist COVID-19 contact tracing efforts, during the 6-week pilot period.

Methods: A 6-week study was conducted on the Vanderbilt University campus in Nashville, Tennessee. The study participants, consisting primarily of graduate students, postdoctoral researchers, and faculty in the Chemistry Department at Vanderbilt University, were asked to use the MyCOVIDKey web app during the course of the study period. Paradata were collected as users engaged with the MyCOVIDKey web app. At the end of the study, all participants were asked to report on their user experience in a survey, and the results were analyzed in the context of the user paradata.

Results: During the pilot period, 45 users enrolled in MyCOVIDKey. An analysis of their enrollment suggests that initial recruiting efforts were effective; however, participant recruitment and engagement efforts at the midpoint of the study were less effective. App use paralleled the number of users, indicating that incentives were useful for recruiting new users to sign up but did not result in users attempting to artificially inflate their use as a result of prize offers. Times to completion of key tasks were low, indicating that the main features of the app could be used quickly. Of the 45 users, 30 provided feedback through a postpilot survey, with 26 (58%) completing it in its entirety. The MyCOVIDKey app as a whole was rated 70.0 on the System Usability Scale, indicating that it performed above the accepted threshold for usability. When the key-in and self-assessment features were examined on their own, it was found that they individually crossed the same thresholds for acceptable usability but that the key-in feature had a higher margin for improvement.

Conclusions: The MyCOVIDKey app was found overall to be a useful tool for COVID-19 contact tracing in a university setting. Most users suggested simple-to-implement improvements, such as replacing the web app framework with a native app format or changing the placement of the scanner within the app workflow. After these updates, this tool could be readily deployed and easily adapted to other settings across the country. The need for digital contact tracing tools is becoming increasingly apparent, particularly as COVID-19 case numbers continue to increase while more businesses begin to reopen.

Keywords: COVID-19; app; contact tracing; mobile health; monitoring; pilot; survey; tracking; usability; usage.

Figure 1

The main screens of the MyCOVIDKey web app: (A) the landing page, which presents a user’s status after a valid login and allows them to access self-assessments and key-ins; B) the login and account creation pages; (C) the screens for CLEAR (left) and NOT CLEAR (right) statuses; (D) the brief COVID-19 risk assessment; and (E) the key-in feature, which enables users to scan location-specific bar codes.

Figure 2

The user signups, screenings, and key-ins for the MyCOVIDKey app over three time periods during the pilot study: week 1, weeks 2-4, and weeks 5-6. The vertical dashed lines at days 6 and 25 represent days on which recruiting emails were distributed.

Figure 3

Screenshots of the user statistics modal in MyCOVIDKey. Users were presented with statistics comparing their app use to that of the rest of the userbase along with their progress toward the maximum number of raffle points allowed each week.

Figure 4

Use of the MyCOVIDKey app by (top) time of day and (bottom) day of week. Time of day is user local time (CST). Total values for reference: 814 logins, 227 screenings, and 1410 key-ins.

Figure 5

System Usability Scale scores for the total MyCOVIDKey app, the screening feature, and the key-in feature. The threshold for acceptable usability of 68 is represented with a dashed horizontal line. The markers represent the scores provided by individual users, and the intensity of the color correlates to the number of logins for that particular user. The maximum color intensity indicates users with more than 50 logins.

Figure 6

The distributions of responses to specific questions about MyCOVIDKey (n=28).

Figure 7

A diagram depicting how MyCOVIDKey users ranked the importance of the features of the app. The questions asked the users (n=26) to identify the most important (blue) and least important (red) features of the app.