Table 1. Parameters of the infectiousness model.

Name	Symbol	Description	Central value	Uncertainty	Source
Parameters directly calculated from data
Doubling time	T2	The time taken for the epidemic to double in size during the early uncontrolled phase of expansion	5.0 days	95% CI: 4.2–6.4	(20)
Incubation period (two parameters)	s(τ)	Lognormal meanlog Lognormal sdlog	1.644 0.363	95% CI: 1.495–1.798 95% CI: 0.201–0.521	(21)
Generation time (two parameters)	w(τ)	Weibull shape Weibull scale	2.826 5.665	95% CI: 1.75–4.7 95% CI: 4.7–6.9	This paper
Parameters with Bayesian priors informed by anecdotal reports or indirect evidence
Proportion asymptomatic	Pa	The proportion of infected individuals who are asymptomatic	0.4	Prior = beta (α = 1.5, β = 1.75) Mode = 0.4 Mean = 0.46	Media reports (Diamond Princess)
Relative infectiousness of asymptomatics	xa	The ratio of infectiousness of asymptomatic individuals to infectiousness of symptomatic individuals	0.1	Prior = beta (α = 1.5, β = 5.5) Mode = 0.1 Mean = 0.21	Observation of few missing links in Singapore outbreak to date [suggestion from (19)]
Fraction of all transmission that is environmentally mediated	RE/R0	Self-explanatory	0.1	Prior = beta (α = 1.5, β = 5.5) Mode = 0.1 Mean = 0.21	Anecdotal observation that many infections can be traced to close contacts once detailed tracing is completed
Environmental infectiousness	E(l)	Rate at which a contaminated environment infects new people after a time lag l	3	Box function (0, n) days, prior for n = gamma (shape = 4, rate = 1) Mode = 3 Mean = 4	(39); variety of values for many different surfaces