Table 1

List of assumptions made to tune the susceptible-infected-removed (SIR) model

Assumptions groupSpecific parameterValueAdditional notesReferences
R0C12,5Average rate of contact between susceptible and infected
individuals
6
τ2,68%Probability of infection given contact between a susceptible and infected individual
d7Duration of infectiousness
Hospitalisation detailsLength of stay of
hospitalised non-ICU patients
87 8
Length of stay of hospitalised ICU patients16
Length of stay in ICU10
Clinical features% of ventilated ICU patients70%9
% of intubated ICU patients50%
% of shock ICU patients35%10
Average days until hospitalisation611
% of mild and moderate cases80%6
Hospitalisation rateInferredDepending on the population’s age group and the corresponding risk of hospitalisation according to Imperial College data8
% hospitalised in ICUInferredDepending on the population’s age group and the corresponding risk of critical care need according to Imperial College data
Testing% mild/moderate cases detected by test10%Percentage of infected individuals with mild or moderate symptoms that will be detected by testing6 12
Non-pharmaceutical interventionsMin Rt with 100% mask compliance0.40Minimum Rt value achieved with all the population wearing masks5
Mask spread reduction0.80% reduction of infectious spread by those infected wearing masks
Mask protection level0.40% protection of those susceptible wearing masks
Min Rt with complete shelter in place0.30Minimum Rt value achieved with all the population sheltering in place
Susceptible shelter in place efficacy0.70Proportion of susceptible who will actually shelter in place
Infected shelter in place efficacy0.90Proportion of infected who will actually shelter in place
Closure NPI min Rt0.60Minimum Rt value achieved with the closure of all the activities, not taking into account masks and sheltering in place
Schools and universities (Rt impact)0,2Maximum contribution provided by the closure of each specific activity (100% compliance) on the Rt value
Large events (Rt impact)0.04
Bars/restaurants (Rt impact)0.18
Offices and factories (Rt impact)0.13
House of worship (Rt impact)0.04
Personal care (Rt impact)0.06
Non-essential retail (Rt impact)0.15
Essential retail (Rt impact)0.13
Entertainment (Rt impact)0.04
Outdoor recreation (Rt impact)0.03
Lag time before NPIs impact the Rt (days), suggested values 14–2121Delay between the date of NPI implementation and the date of their observable maximum impact on the Rt value13
  • NPI, non-pharmaceutical intervention; Rt, R effective.