The effect of non-pharmaceutical interventions on COVID-19 cases, deaths and demand for hospital services in the UK: a modelling study

Nicholas G Davies; Adam J Kucharski; Rosalind M Eggo; Amy Gimma; W. John Edmunds

To calculate ICU and non-ICU beds in use through time, we scaled age-stratified symptomatic cases by age-specific hospitalisation and critical outcome probability, then summed to get the total number of hospitalised and critical cases. We then distributed hospitalised cases over time based on expected time of hospitalisation and duration admitted. We assumed gamma-distributed delays, with the shape parameter set equal to the mean, for: delay from symptom onset to hospitalisation of mean 7 days (standard deviation 2.65) [32, 33] ; delay from hospitalisation to discharge / death for non-ICU patients of mean 8 days (s.d. 2.83) [34] ; delay from hospitalisation to discharge / death for ICU patients of mean 10 days (s.d. 3.16) [33] ; and delay from onset to death of mean 22 days (s.d. 4 .69) [32, 33] .