Table 4.

List of parameters estimated by the ABC model calibration technique, including their corresponding prior distributions

Parameter	Meaning	Prior distribution
${\beta }_1$, ${\beta }_2$, ${\beta }_3$	Transmission parameters	uniform on [0.01, 0.66]
${\beta }_4$, ${\beta }_5$	Transmission parameters	uniform on [0.01, 0.99]
$d_{\mathrm{E}}$	Duration of exposed period	normal: mean 5.08, s.d. 0.5*
$d_{\mathrm{P}}$	Duration of presymptomatic period	uniform on [2, 7]**
$d_{\mathrm{S}}$	Duration of symptomatic period	uniform on [6, 10]
$p_{\mathrm{S}}^1$	Proportion symptomatic for children	uniform on [0.01, 0.99]${}^{††}$
$p_{\mathrm{S}}^2$, $p_{\mathrm{S}}^3$	Proportion symptomatic for adults and seniors	uniform on [0.5, 0.99]${}^{††}$
$p_{\mathrm{T}}^1$, $p_{\mathrm{T}}^2$, $p_{\mathrm{T}}^3$	Proportion going to tests among children, adults, seniors	uniform on [0.5, 0.99]
$r_{\beta }$	Proportional reduction in transmissibility in a/presymptomatic individuals	uniform on [0.4, 1]${}^{†}$
$r_{\mathrm{C}}$	Proportional contact reduction in symptomatic individuals	uniform on [0.01, 0.4]
$p_{\mathrm{P}}$	Proportional reduction in transmission due to personal protection	uniform on [0.01, 0.5]

*Based on He et al. (2020)

**Wei et al. (2020) report 1–3 days

${}^{†}$He et al. (2020) re-analyzed results previously published in local Chinese journals to show a higher probability of virus transmission in symptomatic individuals [the asymptomatic infection rate to be 46% of the symptomatic one, with the 95% CI (18.48–73.60%)], but the source of primary data could not be verified. The value of 0.55 was assumed by Domenico et al. (2020) in setting up their model, based on Li et al. (2020) but for “undocumented” rather than “asymptomatic” patients. On the other hand (Chen et al. 2020), showed no statistically significant difference in the transmissibility of the virus between symptomatic and a/presymptomatic cases

${}^{††}$Estimates vary significantly as does the quality of the evidence. The range of the percentage of the asymptomatic individuals among those positively tested reported is 4.4–89%