A large outbreak of COVID-19 in a UK prison, October 2020 to April 2021

James P. Adamson*, Christopher Smith, Nicole Pacchiarini, Thomas Richard Connor, Janet Wallsgrove, Ian Coles, Clare Frost, Angharad Edwards, Jaisi Sinha, Catherine Moore, Steph Perrett, Christie Craddock, Clare Sawyer, Alison Waldram, Alicia Barrasa, Daniel Rh Thomas, Philip Daniels, Heather Lewis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Prisons are susceptible to outbreaks. Control measures focusing on isolation and cohorting negatively affect wellbeing. We present an outbreak of coronavirus disease 2019 (COVID-19) in a large male prison in Wales, UK, October 2020 to April 2021, and discuss control measures. We gathered case-information, including demographics, staff-residence postcode, resident cell number, work areas/dates, test results, staff interview dates/notes and resident prison-transfer dates. Epidemiological curves were mapped by prison location. Control measures included isolation (exclusion from work or cell-isolation), cohorting (new admissions and work-area groups), asymptomatic testing (case-finding), removal of communal dining and movement restrictions. Facemask use and enhanced hygiene were already in place. Whole-genome sequencing (WGS) and interviews determined the genetic relationship between cases plausibility of transmission. Of 453 cases, 53% (n = 242) were staff, most aged 25-34 years (11.5% females, 27.15% males) and symptomatic (64%). Crude attack-rate was higher in staff (29%, 95% CI 26-64%) than in residents (12%, 95% CI 9-15%). Whole-genome sequencing can help differentiate multiple introductions from person-to-person transmission in prisons. It should be introduced alongside asymptomatic testing as soon as possible to control prison outbreaks. Timely epidemiological investigation, including data visualisation, allowed dynamic risk assessment and proportionate control measures, minimising the reduction in resident welfare.

Original languageEnglish
Pages (from-to)569-570
Number of pages2
JournalEpidemiology and Infection
Publication statusPublished - 30 May 2022

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  • COVID-19
  • epidemiology
  • infectious disease epidemiology
  • outbreaks
  • public health


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