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Nonnenmacher T, Dandamudi N, Futschik ME, Tunkel SA, Kulasegaran-Shylini R, Germanacos N, Cole-Hamilton J, Blandford E, Goddard A, Hillier J, Finer S, Hopkins S, Fowler T. PCR testing of traced contacts for SARS-CoV-2 in England, January to July 2021. Euro Surveill 2023; 28:2300019. [PMID: 37917031 PMCID: PMC10623643 DOI: 10.2807/1560-7917.es.2023.28.44.2300019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 06/16/2023] [Indexed: 11/03/2023] Open
Abstract
BackgroundThe NHS Test and Trace (NHSTT) programme was established in May 2020 in England to deliver SARS-CoV-2 testing and contact tracing in order to identify infected individuals and reduce COVID-19 spread. To further control transmission, people identified as contacts were asked to self-isolate for 10 days and test only if they became symptomatic. From March 2021, eligibility criteria for PCR testing expanded to include asymptomatic contacts of confirmed cases.AimTo analyse testing patterns of contacts before and after the change in testing guidance in England to assess the impact on PCR testing behaviour with respect to symptom status and contact type.MethodsTesting and contact tracing data were extracted from the national data systems and linked. Subsequently, descriptive statistical analysis was applied to identify trends in testing behaviour.ResultsBetween 1 January and 31 July 2021, over 5 million contacts were identified and reached by contact tracers; 42.3% took a PCR test around the time they were traced. Overall positivity rate was 44.3% and consistently higher in symptomatic (60-70%) than asymptomatic (around 20%, March-June) contacts. The proportion of tests taken by asymptomatic contacts increased over time, especially after the change in testing guidance. No link was observed between uptake of PCR tests and vaccination coverage. Fully vaccinated contacts showed lower positivity (23.8%) than those with one dose (37.2%) or unvaccinated (51.0%).ConclusionAlmost 1 million asymptomatic contacts were tested for SARS-CoV-2, identifying 214,056 positive cases, demonstrating the value of offering PCR testing to this group.
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Affiliation(s)
| | | | - Matthias Erwin Futschik
- Faculty of Health, School of Biomedical Sciences, University of Plymouth, Plymouth, United Kingdom
- United Kingdom Health Security Agency, London, United Kingdom
| | - Sarah A Tunkel
- United Kingdom Health Security Agency, London, United Kingdom
| | | | - Nick Germanacos
- United Kingdom Health Security Agency, London, United Kingdom
| | | | | | - Ashley Goddard
- United Kingdom Health Security Agency, London, United Kingdom
| | - Joe Hillier
- United Kingdom Health Security Agency, London, United Kingdom
| | - Stephen Finer
- United Kingdom Health Security Agency, London, United Kingdom
| | - Susan Hopkins
- United Kingdom Health Security Agency, London, United Kingdom
| | - Tom Fowler
- William Harvey Research Institute, Queen Mary University of London, London, United Kingdom
- United Kingdom Health Security Agency, London, United Kingdom
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Young BC, Eyre DW, Kendrick S, White C, Smith S, Beveridge G, Nonnenmacher T, Ichofu F, Hillier J, Oakley S, Diamond I, Rourke E, Dawe F, Day I, Davies L, Staite P, Lacey A, McCrae J, Jones F, Kelly J, Bankiewicz U, Tunkel S, Ovens R, Chapman D, Bhalla V, Marks P, Hicks N, Fowler T, Hopkins S, Yardley L, Peto TEA. Daily testing for contacts of individuals with SARS-CoV-2 infection and attendance and SARS-CoV-2 transmission in English secondary schools and colleges: an open-label, cluster-randomised trial. Lancet 2021; 398:1217-1229. [PMID: 34534517 PMCID: PMC8439620 DOI: 10.1016/s0140-6736(21)01908-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 12/21/2022]
Abstract
BACKGROUND School-based COVID-19 contacts in England have been asked to self-isolate at home, missing key educational opportunities. We trialled daily testing of contacts as an alternative to assess whether this resulted in similar control of transmission, while allowing more school attendance. METHODS We did an open-label, cluster-randomised, controlled trial in secondary schools and further education colleges in England. Schools were randomly assigned (1:1) to self-isolation of school-based COVID-19 contacts for 10 days (control) or to voluntary daily lateral flow device (LFD) testing for 7 days with LFD-negative contacts remaining at school (intervention). Randomisation was stratified according to school type and size, presence of a sixth form, presence of residential students, and proportion of students eligible for free school meals. Group assignment was not masked during procedures or analysis. Coprimary outcomes in all students and staff were COVID-19-related school absence and symptomatic PCR-confirmed COVID-19, adjusted for community case rates, to estimate within-school transmission (non-inferiority margin <50% relative increase). Analyses were done on an intention-to-treat basis using quasi-Poisson regression, also estimating complier average causal effects (CACE). This trial is registered with the ISRCTN registry, ISRCTN18100261. FINDINGS Between March 18 and May 4, 2021, 204 schools were taken through the consent process, during which three decided not to participate further. 201 schools were randomly assigned (control group n=99, intervention group n=102) in the 10-week study (April 19-May 10, 2021), which continued until the pre-appointed stop date (June 27, 2021). 76 control group schools and 86 intervention group schools actively participated; additional national data allowed most non-participating schools to be included in analysis of coprimary outcomes. 2432 (42·4%) of 5763 intervention group contacts participated in daily contact testing. There were 657 symptomatic PCR-confirmed infections during 7 782 537 days-at-risk (59·1 per 100 000 per week) in the control group and 740 during 8 379 749 days-at-risk (61·8 per 100 000 per week) in the intervention group (intention-to-treat adjusted incidence rate ratio [aIRR] 0·96 [95% CI 0·75-1·22]; p=0·72; CACE aIRR 0·86 [0·55-1·34]). Among students and staff, there were 59 422 (1·62%) COVID-19-related absences during 3 659 017 person-school-days in the control group and 51 541 (1·34%) during 3 845 208 person-school-days in the intervention group (intention-to-treat aIRR 0·80 [95% CI 0·54-1·19]; p=0·27; CACE aIRR 0·61 [0·30-1·23]). INTERPRETATION Daily contact testing of school-based contacts was non-inferior to self-isolation for control of COVID-19 transmission, with similar rates of symptomatic infections among students and staff with both approaches. Infection rates in school-based contacts were low, with very few school contacts testing positive. Daily contact testing should be considered for implementation as a safe alternative to home isolation following school-based exposures. FUNDING UK Government Department of Health and Social Care.
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Affiliation(s)
| | - David W Eyre
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK; Big Data Institute, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | | | - Chris White
- Department of Health and Social Care, London, UK
| | | | | | | | - Fegor Ichofu
- Department of Health and Social Care, London, UK
| | | | - Sarah Oakley
- Microbiology Department, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | | | | | - Fiona Dawe
- Office for National Statistics, Newport, UK
| | - Ieuan Day
- Office for National Statistics, Newport, UK
| | | | | | | | | | | | | | | | - Sarah Tunkel
- Department of Health and Social Care, London, UK
| | | | | | | | - Peter Marks
- Department of Health and Social Care, London, UK
| | - Nick Hicks
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK; Department of Health and Social Care, London, UK; Public Health England, London, UK
| | - Tom Fowler
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | | | - Lucy Yardley
- Health Protection Research Unit in Behavioural Science, University of Bristol, Bristol, UK; School of Psychology, University of Southampton, Southampton, UK
| | - Tim E A Peto
- Nuffield Department of Medicine, University of Oxford, Oxford, UK; National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, UK; NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, University of Oxford, Oxford, UK
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