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Association of COVID-19 Quarantine Duration and Postquarantine Transmission Risk in 4 University Cohorts

Educational Objective
To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  What is the risk of SARS-CoV-2 transmission from individuals leaving test-based quarantines of various durations?

Findings  In this cohort study of 301 quarantined university students and staff who tested positive for COVID-19, 40 (13.3%) tested negative and were asymptomatic on day 7, implying an approximate 13% postquarantine transmission risk for 7-day test-based quarantine.

Meaning  To maintain the 5% transmission risk used as the basis for the 7-day guideline, our data suggest that quantitative polymerase chain reaction test–based, nonstrict quarantine should be 10 days.

Abstract

Importance  Optimal quarantine length for COVID-19 infection is unclear, in part owing to limited empirical data.

Objective  To assess postquarantine transmission risk for various quarantine lengths and potential associations between quarantine strictness and transmission risk.

Design, Setting, and Participants  Retrospective cohort study in 4 US universities from September 2020 to February 2021, including 3641 university students and staff who were identified as close contacts to individuals who tested positive for SARS-CoV-2 infection. Individuals were tested throughout the 10 to 14–day quarantine, and follow-up testing continued at least weekly throughout the 2020-2021 academic year.

Exposures  Strict quarantine, including designated housing with a private room, private bathroom, and meal delivery, vs nonstrict, which potentially included interactions with household members.

Main Outcomes and Measures  Dates of last known exposure, last negative test result, and first positive test result during quarantine.

Results  This study included 301 quarantined university students and staff who tested SARS-CoV-2–positive (of 3641 quarantined total). These 301 individuals had a median (IQR) age of 22.0 (20.0-25.0) years; 131 (43.5%) identified as female; and 20 (6.6%) were staff. Of the 287 self-reporting race and ethnicity according to university-defined classifications, 21 (7.3%) were African American or Black, 60 (20.9%) Asian, 17 (5.9%) Hispanic or Latinx, 174 (60.6%) White, and 15 (5.2%) other (including multiracial and/or multiethnic). Of the 301 participants, 40 (13.3%; 95% CI, 9.9%-17.6%) had negative test results and were asymptomatic on day 7 compared with 15 (4.9%; 95% CI, 3.0%-8.1%) and 4 (1.4%; 95% CI, 0.4%-3.5%) on days 10 and 14, respectively. Individuals in strict quarantine tested positive less frequently than those in nonstrict quarantine (10% vs 12%; P = .04).

Conclusions and Relevance  To maintain the 5% transmission risk used as the basis for US Centers for Disease Control and Prevention’s 7-day test-based quarantine guidance, our data suggest that quarantine with quantitative polymerase chain reaction testing 1 day before intended release should be 10 days for nonstrict quarantine and 8 days for strict quarantine, as ongoing exposure during quarantine may be associated with the higher rate of positive test results following nonstrict quarantine.

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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.

Article Information

Accepted for Publication: December 6, 2021.

Published: February 25, 2022. doi:10.1001/jamanetworkopen.2022.0088

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Liu AB et al. JAMA Network Open.

Corresponding Author: Michael Springer, PhD, Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Armenise 545A, Boston, MA 02115 (michael_springer@hms.harvard.edu).

Author Contributions: Mr Liu and Dr Springer had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Liu, Yune, Hamer, Springer.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Liu, Davidi, Landsberg, Francesconi, Platt, Yune, Puglin, Hamer, Springer.

Critical revision of the manuscript for important intellectual content: Liu, Davidi, Landsberg, Nguyen, Yune, Deckard, Haase, Hamer.

Statistical analysis: Liu, Davidi, Puglin, Springer.

Administrative, technical, or material support: Landsberg, Francesconi, Nguyen, Haase, Springer.

Supervision: Hamer, Springer.

Conflict of Interest Disclosures: Dr Deckard reported employment with Geometric Data Analytics and research support from the Defense Advanced Research Projects Agency and the National Science Foundation. No other disclosures were reported.

Additional Contributions: We thank Becky Ward, PhD (Harvard Medical School, Boston, Massachusetts), and Ron Milo, PhD (Weizmann Institute of Science, Rehovot, Israel), for helpful discussions and feedback on the manuscript. We obtained written permission to include these individuals in the acknowledgments. They were not compensated for their contributions.

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