Symbol  Description  Uniform prior (min and max) or point estimate
1 / η  Duration of the non-infectious exposure period  5.1 days41
δ  Percentage of infections which become symptomatic  82.1%42; vary between 73.15% and 91.05%
1 / μ  Duration of symptoms while not hospitalised (independent of outcome)  Vary between 2 and 14 days
1 / ρ  Duration of stay in acute bed (independent of outcome)  Vary between 2 and 14 days
γ  g  Percentage of symptomatic cases which will require hospitalisation  0–4=0.00%, 5–17=0.0408%, 18–29=1.04%,30–39=2.04%–7.00%, 40–49=2.53%–8.68%,50–59=4.86%–16.7%, 60–69=7.01%–24.0%,70+=9.87%–37.6%16
1 / ψ  Duration of stay in IC bed (independent of outcome)  3–11 days43
ϵ  Percentage of those requiring hospitalisation who will require IC  Vary between 0% and 30%
ω  g  Percentage of those requiring IC who will die  0–4=0.00%, 5–17=0.00%, 18–29=18.1%,30–39=18.1%, 40–49=24.7%,50–59=39.3%, 60–69=53.9%,70+=65.3%43
κ  Percentage of those requiring acute beds (but not IC) who will die  Vary between 5% and 35%
school  Percentage of 0–18 year-olds attending school after 23 March 2020  Assume 5%
distancing  Percentage reduction in contact rates due to social distancing after 15 March 2020  Vary between 0% and 50%
lockdown  Percentage reduction in contact rates due to lockdown after 23 March 2020  Retail/recreation: Bristol 86%, Bath 90%, Plymouth 85%, Gloucs 84%, Somerset 82%, Devon 85%, Dorset 84%44Transit stations: Bristol 78%, Bath 71%, Plymouth 65%, Gloucs 69%, Somerset 67%, Devon 66%, Dorset 63%44Vary between 63% and 90%
R  0  Initial reproductive number of COVID-19  1.63–3.9524
endphase  Time taken to fully adjust (across the population, on average) to new interventions  Vary between 1 and 31 days