Table 2.

Control measures used at Prison A, before and during outbreak

Description	Residents	Staff	Details
Control measures already in place when outbreak declared
Enhanced cleaning	✓	✓	Hand-washing stations and 70%-alcohol-gel dispensers installed in all areas.
Safety briefings	✓	✓	Regular reiteration of importance of hand hygiene and social distancing.
Mandatory face coverings	✓	✓	Signage installed throughout the prison; all-persons challenge to reinforce these rules.
Reduced room capacity	✓	✓	Risk assessment based on internal area of all communal/meeting rooms to allow at least 2 metres distance between people Signage stating maximum occupancy on door.
Sub-group socialisation		✓	Staggered socialisation times, when mixing was permitted, to reduce mixing and aid social distancing.
Control measures introduced during this outbreak
Vaccination		✓	Vaccinated by age-cohort in line with general population priority (staff offered vaccination in community clinics).
Control measures introduced by the OCT
Exclusion	✓	✓	Symptomatic staff were excluded from work, asked to take a PCR test and remained in self-isolation until the result was known. Symptomatic residents took a PCR test and remained in cell-isolation pending results. Where cells were shared, contact formed a ‘bubble’; they followed the same isolation period as cellmate, dependent on results.
Reverse cohorting		✓	New resident-admissions, from courts system or inter-prison transfer, were reverse-cohorted by date to limit transmission in either direction between people living and working in A-block.
Asymptomatic testing	✓	✓	Asymptomatic testing (day one and day five PCR tests) implemented for new resident-admissions from December 2020. Admissions grouped by admission date until 14 days after arrival before commencement of the induction-programme and relocation to another permanent residential-block. The testing team provided peripatetic testing for residents at accommodation blocks and testing for all staff based on a shift pattern.
Minimising mixing	✓	✓	To minimise new introductions and person-to-person transmission, staff worked in one area only, unless operationally necessary otherwise. Staff overtime was restricted to the same area as normal hours. Staff dining became takeaway during March 2020. Staff were frequently advised not to car share. Residents performing essential work (kitchen, cleaning and laundry) were organised into shift-groups so residents from the same accommodation unit worked together. Non-essential work was limited or stopped during level four restrictions.
Cell isolation (‘level four’ restrictions)		✓	The highest level of restrictions (‘level four’) were initiated in mid-December 2020 to control case rate the outbreak's peak This included suspension of visits, non-essential work and staff-movement across prison. Residents limited to 30-min per day to shower and exercise outside cells. Meals and purchases were brought to cells.