Abstract
ObjectiveIn September 2020, 15 861 SARS-CoV-2 case records failed to upload from the Second Generation Surveillance System (SGSS) to the Contact Tracing Advisory Service (CTAS) tool, delaying the contact tracing of these cases. This study used CTAS data to determine the impact of this delay on population health outcomes: transmission events, hospitalisations and mortality. Previously, a modelling study suggested a substantial impact.DesignObservational study.SettingEngland.PopulationIndividuals testing positive for SARS-CoV-2 and their reported contacts.Main outcome measuresSecondary attack rates (SARs), hospitalisations and deaths among primary and secondary contacts were calculated, compared with all other concurrent, unaffected cases. Affected SGSS records were matched to CTAS records. Successive contacts and cases were identified and matched to hospital episode and mortality outcomes.ResultsInitiation of contact tracing was delayed by 3 days on average in the primary cases in the delay group (6 days) compared with the control group (3 days). This was associated with lower completion of contact tracing: 80% (95% CI: 79% to 81%) in delay group and 83% (95% CI: 83% to 84%) in control group. There was some evidence to suggest increased transmission to non-household contacts among those affected by the delay. The SAR for non-household contacts was higher among secondary contacts in the delay group than the control group (delay group: 7.9%, 95% CI: 6.5% to 9.2%; control group: 5.9%, 95% CI: 5.3% to 6.6%). There did not appear to be a significant difference between the delay and control groups in the odds of hospitalisation (crude OR: 1.1 (95% CI: 0.9 to 1.2)) or death (crude OR: 0.7 (95% CI: 0.1 to 4.0)) among secondary contacts.ConclusionsOur analysis suggests that the delay in contact tracing had a limited impact on population health outcomes; however, contact tracing was not completed for all individuals, so some transmission events might not be captured.
Funder
UK Research and Innovation
National Institute for Health Research Health Protection Research Unit
Programme Grants for Applied Research
Reference31 articles.
1. UK Government . Coronavirus (COVID-19) in the UK. UK summary. 2021. Available: https://coronavirus.data.gov.uk [Accessed 09 October 2023].
2. Public Health England . NHS test and trace. 2021. Available: https://contact-tracing.phe.gov.uk [Accessed 01 Dec 2021].
3. Public Health England . Letter from Richard Gleave, deputy chief executive of public health England, describing the use of CTAS in the COVID-19 response. 2020. Available: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/881231/Letter_to_DsPH_on_contact_tracing.pdf [Accessed 01 Dec 2021].
4. Efficacy of contact tracing for the containment of the 2019 novel coronavirus (COVID-19)
5. Public Health England . PHE statement on delayed reporting of COVID-19 cases. 2020. Available: https://www.gov.uk/government/news/phe-statement-on-delayed-reporting-of-covid-19-cases [Accessed 01 Dec 2021].