Comparison of Home Antigen Testing With RT-PCR and Viral Culture During the Course of SARS-CoV-2 Infection
Authors: Chu Victoria T. , Schwartz Noah G. , Donnelly Marisa A. P. , Chuey Meagan R. , Soto Raymond , Yousaf Anna R. , Schmitt-Matzen Emily N. , Sleweon Sadia , Ruffin Jasmine , Thornburg Natalie , Harcourt Jennifer L. , Tamin Azaibi , Kim Gimin , Folster Jennifer M. , Hughes Laura J. , Tong Suxiang , Stringer Ginger , Albanese Bernadette A. , Totten Sarah E. , Hudziec Meghan M. , Matzinger Shannon R. , Dietrich Elizabeth A. , Sheldon Sarah W. , Stous Sarah , McDonald Eric C. , Austin Brett , Beatty Mark E. , Staples J. Erin , Killerby Marie E. , Hsu Christopher H. , Tate Jacqueline E. , Kirking Hannah L. , Matanock Almea ,   COVID-19 Household Transmission Team, Abara Winston E. , Alexander Lorraine N. , Arons Melissa M. , Firestone Melanie J. , Foster Monique A. , Garza Elizabeth , Gomez Yessica , Guagliardo Sarah Anne J. , Haberling Dana L. , Humrighouse Ben W. , Konkle Stacey L. , Marcenac Perrine , Monroe Benjamin P. , Namageyo-Funa Apophia , O’Hegarty Michelle , Pratt Caroline Q. , Pray Ian W. , Robinson Byron F. , Ruiseñor-Escudero Horacio , Segaloff Hannah E. , Shragai Talya , Somers Tarah S. , Tobolowsky Farrell A. , Zacks Rachael L. Ticho , Anderson Raydel D. , Chakrabarti Ayan K. , Cherney Blake , LaVoie Stephen P. , Mitchell Kaitlin F. , Morgan Clint N. , Rossetti Rebecca , Stoddard Robyn A. , Vuong Jeni , Whaley Melissa J. , Castro Georgi Joaudimir , Chancey Rebecca J , Figueroa Erica , Lehman Jennifer , Lindell Kristine , Magleby Reed , Marx Grace E. , McCormick David W. , Mead Paul , Ruth Laird J. , Silver Maggie , Visser Susanna N. , Waltenburg Michelle A. , Boroughs Karen L , Brault Aaron C. , Drexler Anna , McAllister Janet , Pawloski Jamie , Stovall Janae , Dionicio Bernabe Maria I. , Manlutac Anna Liza M. , Zuniga-Groot Graciela , Jain Seema , Baily Heather , Burakoff Alexis , Grano Christopher , Webb Lindsey Martin , Alvarez Evelyn , Bundalian Cassandra N , Collins Hannah , Delmonico Christopher , Dunyak Shaun , Fortune Hannah M , Giddmore Wyatt , Huynh-Templeman Kimberly , Ling Tia , Olsen Hunter , Pysnack Nicholas J , Ricci Aleigha M , Stitzlein Tara M. , Drobeniuc Jan , Weis-Torres Sabrina , Punkova Lili , Jia Tao Lily , Browning Peter , Bolcen Shanna , Maniatis Panagiotis , Park So Hee , Moss Kimberly M. , Zellner Briana , Ortiz Kristina , Uehara Anna , Retchless Adam C. , Tao Ying , Li Yan , Kelleher Anna , NG Han Jia Justin , Zhang Jing , Lynch Brian , Cook Peter W. , Paden Clinton R. , Queen Krista , Medrzycki Magdalena , Rogers Shannon , Wong Phili , Jain Shilpi , Tejada-Strop Alexandra , Metz John Michael , David Ebenezer , Tang Xiaoling , Wynn Nhien T. , Tiller Rebekah , Sakthivel Senthilkumar K. , Velusamy Srinivasan , Whitaker Brett , Petway Marla E. 
Published: April 2022

Importance

As self-collected home antigen tests become widely available, a better understanding of their performance during the course of SARS-CoV-2 infection is needed.

Objective

To evaluate the diagnostic performance of home antigen tests compared with reverse transcription–polymerase chain reaction (RT-PCR) and viral culture by days from illness onset, as well as user acceptability.

Design, Setting, and Participants

This prospective cohort study was conducted from January to May 2021 in San Diego County, California, and metropolitan Denver, Colorado. The convenience sample included adults and children with RT-PCR–confirmed infection who used self-collected home antigen tests for 15 days and underwent at least 1 nasopharyngeal swab for RT-PCR, viral culture, and sequencing.

Exposures

SARS-CoV-2 infection.

Main Outcomes and Measures

The primary outcome was the daily sensitivity of home antigen tests to detect RT-PCR–confirmed cases. Secondary outcomes included the daily percentage of antigen test, RT-PCR, and viral culture results that were positive, and antigen test sensitivity compared with same-day RT-PCR and cultures. Antigen test use errors and acceptability were assessed for a subset of participants.

Results

This study enrolled 225 persons with RT-PCR–confirmed infection (median [range] age, 29 [1-83] years; 117 female participants [52%]; 10 [4%] Asian, 6 [3%] Black or African American, 50 [22%] Hispanic or Latino, 3 [1%] Native Hawaiian or Other Pacific Islander, 145 [64%] White, and 11 [5%] multiracial individuals) who completed 3044 antigen tests and 642 nasopharyngeal swabs. Antigen test sensitivity was 50% (95% CI, 45%-55%) during the infectious period, 64% (95% CI, 56%-70%) compared with same-day RT-PCR, and 84% (95% CI, 75%-90%) compared with same-day cultures. Antigen test sensitivity peaked 4 days after illness onset at 77% (95% CI, 69%-83%). Antigen test sensitivity improved with a second antigen test 1 to 2 days later, particularly early in the infection. Six days after illness onset, antigen test result positivity was 61% (95% CI, 53%-68%). Almost all (216 [96%]) surveyed individuals reported that they would be more likely to get tested for SARS-CoV-2 infection if home antigen tests were available over the counter.

Conclusions and Relevance

The results of this cohort study of home antigen tests suggest that sensitivity for SARS-CoV-2 was moderate compared with RT-PCR and high compared with viral culture. The results also suggest that symptomatic individuals with an initial negative home antigen test result for SARS-CoV-2 infection should test again 1 to 2 days later because test sensitivity peaked several days after illness onset and improved with repeated testing.