Abstract
Background: In the UK, during the study period all COVID-19 contacts were required to self-isolate for 10 days, which had adverse impacts. Avoiding the need to self-isolate for those who remain uninfected would be beneficial to society. We investigated whether using daily lateral flow devices (LFDs) to test for COVID-19 with removal of self-isolation for 24 hours if negative was a safe alternative to self-isolation by determining tertiary attack rates (proportion being infected) in study groups.
Methods: We conducted a non-inferiority randomised controlled trial (Research Registry ID:6809) in adult contacts identified during COVID-19 contact tracing. Consented participants were randomised to self-isolation (SI; single PCR, 10 days isolation) or daily contact-testing (DCT; 7 LFDs, 2 PCRs, no isolation if negative on LFD);participants from a household were assigned to the same arm. Participants were prospectively followed-up with the impact of each intervention on onward transmission determined from routinely collected contact tracing data for COVID-19 participants, and tertiary cases arising from their contacts. Attack rates were derived from cluster-robust standard error Bernoulli regression models. Questionnaires were sent at recruitment and at the end of testing/self-isolation to assess behaviours.
Findings: 49,623 individuals consented to participate with final arm allocations of 26,123 DCT (52.6%) and 23,500 SI participants (47.4%). Overall. 4,561 participants tested positive by PCR (secondary cases); 2,359 (10.0%) in the SI arm and 2,202 (8.4%) in the DCT arm. Tertiary attack rates (among secondary contacts) were 7.5% in SI arm and 6.4% in DCT arm (difference of -1.1 % (95% Confidence Interval -2.2% to -0.03%)), significantly lower than the non-inferiority margin of 1.9%.124,010 valid LFD results were reported from 20,795 (79.6%) DCT participants with 1,132 (5.4%) reporting a positive result.
Interpretation: DCT with 24-hour exemption from self-isolation for essential activities appears to be non-inferior to self-isolation.
Interpretation: DCT with 24-hour exemption from self-isolation for essential activities appears to be non-inferior to self-isolation.
Methods: We conducted a non-inferiority randomised controlled trial (Research Registry ID:6809) in adult contacts identified during COVID-19 contact tracing. Consented participants were randomised to self-isolation (SI; single PCR, 10 days isolation) or daily contact-testing (DCT; 7 LFDs, 2 PCRs, no isolation if negative on LFD);participants from a household were assigned to the same arm. Participants were prospectively followed-up with the impact of each intervention on onward transmission determined from routinely collected contact tracing data for COVID-19 participants, and tertiary cases arising from their contacts. Attack rates were derived from cluster-robust standard error Bernoulli regression models. Questionnaires were sent at recruitment and at the end of testing/self-isolation to assess behaviours.
Findings: 49,623 individuals consented to participate with final arm allocations of 26,123 DCT (52.6%) and 23,500 SI participants (47.4%). Overall. 4,561 participants tested positive by PCR (secondary cases); 2,359 (10.0%) in the SI arm and 2,202 (8.4%) in the DCT arm. Tertiary attack rates (among secondary contacts) were 7.5% in SI arm and 6.4% in DCT arm (difference of -1.1 % (95% Confidence Interval -2.2% to -0.03%)), significantly lower than the non-inferiority margin of 1.9%.124,010 valid LFD results were reported from 20,795 (79.6%) DCT participants with 1,132 (5.4%) reporting a positive result.
Interpretation: DCT with 24-hour exemption from self-isolation for essential activities appears to be non-inferior to self-isolation.
Interpretation: DCT with 24-hour exemption from self-isolation for essential activities appears to be non-inferior to self-isolation.
| Original language | English |
|---|---|
| Pages (from-to) | 1074-1085 |
| Number of pages | 12 |
| Journal | Lancet Respiratory Medicine |
| Volume | 10 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 10 Oct 2022 |
Bibliographical note
Funding Information:Funding was provided by the UK Government Department of Health and Social Care. AFM is supported by the Economic and Social Research Council (grant number ES/J500057/1). We would like to thank the following teams for supporting the delivery of the trial: logistical and operational support from the NHS Test & Trace daily contact testing and home delivery teams (UKHSA and Department of Health and Social Care); recruitment support from the Agile Lighthouse team (UKHSA), NHSTT call handlers, and NHS 119 call handlers; administrative and mailbox support from the contact tracing administration team (UKHSA); data linkage by the Second Generation Surveillance System team and Field Service South West (UKHSA); and data support and advice from EpiCell and Contact tracing teams (UKHSA).
Publisher Copyright:
© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
Research Groups and Themes
- Physical and Mental Health
- Covid19
Keywords
- COVID-19
- SARS-CoV-2
- Lateral flow testing
- Contacts
- testing
- DCT
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