Fig. 1.

Overview of the model structure. (A) The structure of the care home and routes of introducing SARS-CoV-2 into the home. The base case care home, representative of a care home in North Lanarkshire, Scotland, has 80 residents and a team of 72 staff members. It is split into 2 units containing 40 residents and 16 and 15 care staff members on duty per unit per day. The staff pools for the 2 units contain 33 and 32 care staff members respectively. A group of 7 well-being coordinators and housekeepers is shared between the 2 units. (B) The progression of COVID-19 cases. Susceptible people may acquire the infection when exposed to infectious sources. They are infected but not yet infectious (exposed state). Once exposed people become infectious, they can either remain asymptomatic for the entire infectious period or develop symptoms after a pre-symptomatic period. Symptoms could be mild or severe and require hospitalizations. Infectious people will eventually recover or die. (C) Interactions between residents, staff and visitors in a care home. The dashed lines linking individuals denote their possible ways of interaction. Different colours are used for these lines to distinguish different types of interaction: blue, staff-resident interaction; green, resident-resident interaction; red, staff–staff interaction; black, resident-visitor interaction; and purple, staff–visitor interactions.