Finding a Needle in the Haystack: Design and Implementation of a Digital Site-less Clinical Study of Serial Rapid Antigen Testing to Identify Asymptomatic SARS-CoV-2 Infection [preprint]

Abstract

Background: Over-the-counter rapid antigen tests for SARS-CoV-2 with an Emergency Use Authorization (EUA) in the United States generally include a condition of authorization to evaluate the test's performance in asymptomatic individuals when used serially. A goal of this study was to investigate the performance of SARS-CoV-2 antigen serial testing and generate data to support regulatory decisions.

Objective: To describe a novel study design to evaluate serial use of rapid antigen tests in detecting SARS-CoV-2 virus among asymptomatic individuals.

Design: Prospective cohort study using a decentralized approach. Eligible participants from across the U.S. could enroll and complete this study from their home environment through a study app. Participant enrollment was prioritized based on regional 7-day case rates, participants' vaccination status, and sociodemographic characteristics prior to enrollment.Prioritization criteria were adjusted on a daily or weekly basis. Enrolled participants were mailed rapid antigen tests and molecular comparator collection kits and asked to test every 48 hours for 15 days. Three companies' rapid antigen tests were used in the study; assignment of participant to a test was criteria-based and non-random, precluding head-to-head comparison between the tests.

Participants: Mainland United States residents over 2 years old with no reported COVID-19 symptoms in the 14 days prior to study enrollment.

Main measures: Participant demographics, COVID-19 vaccination status, and geographic distribution were used to understand the impact of the site-less recruitment and enrollment strategy.

Key results: A total of 7,361 participants enrolled in the study between October 18, 2021 and February 15, 2022. Throughout the study, 369 participants tested positive for SARS-CoV-2, including 167 who were asymptomatic and tested negative on SARS-CoV-2 molecular assays to start the study. This exceeded the initial enrollment goals of 60 positive participants. We enrolled participants from 44 of the 48 mainland U.S. states, and geographic distribution of participants shifted in accordance with the changing COVID-19 prevalence nationwide.

Conclusions: The novel, digital site-less approach employed in the 'Test Us At Home' study enabled rapid, efficient, and rigorous evaluation of rapid diagnostics for COVID-19, and can be adapted across research disciplines to optimize study enrollment and accessibility.