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Daily use of lateral flow devices by contacts of confirmed COVID-19 cases to enable exemption from isolation compared with standard self-isolation to reduce onward transmission of SARS-CoV-2 in England: a randomised, controlled, non-inferiority trial

Daily use of lateral flow devices by contacts of confirmed COVID-19 cases to enable exemption from isolation compared with standard self-isolation to reduce onward transmission of SARS-CoV-2 in England: a randomised, controlled, non-inferiority trial
Daily use of lateral flow devices by contacts of confirmed COVID-19 cases to enable exemption from isolation compared with standard self-isolation to reduce onward transmission of SARS-CoV-2 in England: a randomised, controlled, non-inferiority trial
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.
Contacts, Covid-19, DCT, Lateral Flow Testing, SARS-CoV-2, Testing
2213-2600
1074-1085
Love, Nicola
f3f4f2aa-af53-4062-91e0-21b798a72f3e
Ready, Derren
bc11ef15-b8f9-4372-9750-fd9c55981796
Turner, Charlie
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Verlander, Neville
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French, Clare
629c6728-19a8-421c-9356-ebd6cd588d50
Martin, Alex
e137f6f2-bc93-4939-b56c-9ff52b8d9fd9
Sorensen, Tina
d46f3e7d-4cde-4a14-8176-4709919579e6
Metelmann, Soeren
fdc53ff2-77bb-423b-9237-402ca24702fa
Denford, Sarah
8970b5a7-8cad-4356-ad0e-88297b67db37
Rubin, James
a1b1aed4-81d0-4a77-9731-988d6e242344
Yardley, Lucy
64be42c4-511d-484d-abaa-f8813452a22e
Amlot, Richard
d93f5263-ea24-4b12-b505-f51694220b8e
Hopkins, Susan
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Oliver, Isabel
1598f598-b35d-42a4-9695-9b57c5ab15e9
Love, Nicola
f3f4f2aa-af53-4062-91e0-21b798a72f3e
Ready, Derren
bc11ef15-b8f9-4372-9750-fd9c55981796
Turner, Charlie
2d50607d-3fdf-4859-8c63-592c51d02395
Verlander, Neville
0e2b5dfc-a536-4698-a282-e072227ff86b
French, Clare
629c6728-19a8-421c-9356-ebd6cd588d50
Martin, Alex
e137f6f2-bc93-4939-b56c-9ff52b8d9fd9
Sorensen, Tina
d46f3e7d-4cde-4a14-8176-4709919579e6
Metelmann, Soeren
fdc53ff2-77bb-423b-9237-402ca24702fa
Denford, Sarah
8970b5a7-8cad-4356-ad0e-88297b67db37
Rubin, James
a1b1aed4-81d0-4a77-9731-988d6e242344
Yardley, Lucy
64be42c4-511d-484d-abaa-f8813452a22e
Amlot, Richard
d93f5263-ea24-4b12-b505-f51694220b8e
Hopkins, Susan
8d271e32-f2bd-4ade-ba99-5b98ef0a007c
Oliver, Isabel
1598f598-b35d-42a4-9695-9b57c5ab15e9

Love, Nicola, Ready, Derren, Turner, Charlie, Verlander, Neville, French, Clare, Martin, Alex, Sorensen, Tina, Metelmann, Soeren, Denford, Sarah, Rubin, James, Yardley, Lucy, Amlot, Richard, Hopkins, Susan and Oliver, Isabel (2022) Daily use of lateral flow devices by contacts of confirmed COVID-19 cases to enable exemption from isolation compared with standard self-isolation to reduce onward transmission of SARS-CoV-2 in England: a randomised, controlled, non-inferiority trial. The Lancet Respiratory Medicine, 10 (11), 1074-1085. (doi:10.1016/S2213-2600(22)00267-3).

Record type: Article

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.

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LOVE - Lancet Res Med - Non-inferiority RCT onward infection transmission COVID - Accepted Manuscript
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Accepted/In Press date: 12 July 2022
e-pub ahead of print date: 10 October 2022
Additional 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).
Keywords: Contacts, Covid-19, DCT, Lateral Flow Testing, SARS-CoV-2, Testing

Identifiers

Local EPrints ID: 468878
URI: http://eprints.soton.ac.uk/id/eprint/468878
ISSN: 2213-2600
PURE UUID: 39342f17-a623-44ba-98d6-4373a367a646
ORCID for Lucy Yardley: ORCID iD orcid.org/0000-0002-3853-883X

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Date deposited: 31 Aug 2022 16:43
Last modified: 22 Nov 2022 05:01

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Contributors

Author: Nicola Love
Author: Derren Ready
Author: Charlie Turner
Author: Neville Verlander
Author: Clare French
Author: Alex Martin
Author: Tina Sorensen
Author: Soeren Metelmann
Author: Sarah Denford
Author: James Rubin
Author: Lucy Yardley ORCID iD
Author: Richard Amlot
Author: Susan Hopkins
Author: Isabel Oliver

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