Table 3.
Estimated incubation period for confirmed COVID-19 cases stratified by gender, epidemic period, and age group (years).
| Sub-group | Parameter | Log-normal model | Weibull model | Gamma model |
|---|---|---|---|---|
| Gender | ||||
| Male | Mean (95% CI) | 4.98 (4.43–5.09) | 3.78 (3.33–3.97) | 4.59 (4.05–4.71) |
| Median (95% CI) | 4.94 (4.41–5.04) | 4.24 (3.90–4.43) | 4.08 (3.90–4.47) | |
| 95th percentile (95% CI) | 12.62 (11.69–12.97) | 11.11 (10.97–11.49) | 11.04 (10.83–11.89) | |
| AIC | 647.50 | 651.67 | 681.89 | |
| Female | Mean (95% CI) | 4.68 (4.25–4.89) | 3.55 (3.10–3.91) | 4.83 (4.03–4.99) |
| Median (95% CI) | 4.63 (4.23–4.79) | 3.87 (3.11–3.95) | 3.81 (3.21–4.0) | |
| 95th percentile (95% CI) | 12.14 (10.94–12.87) | 11.48 (10.92–11.61) | 11.19 (10.86–11.41) | |
| AIC | 673.27 | 691.57 | 647.41 | |
| Epidemic period | ||||
| Period-1 | Mean (95% CI) | 4.89 (4.33–5.03) | 3.86 (3.31–3.98) | 4.73 (4.22–4.95) |
| Median (95% CI) | 4.81 (4.31–4.99) | 3.96 (3.39–4.01) | 3.87 (3.41–4.83) | |
| 95th percentile (95% CI) | 13.04 (12.77–13.47) | 11.74 (10.45–12.01) | 11.63 (9.98–11.99) | |
| AIC | 787.13 | 800.03 | 793.97 | |
| Period-2 | Mean (95% CI) | 4.47 (4.45–5.01) | 3.82 (3.04–4.01) | 4.39 (3.90–4.69) |
| Median (95% CI) | 4.44 (4.41–4.59) | 3.86 (3.33–3.99) | 3.87 (3.43–3.98) | |
| 95th percentile (95% CI) | 10.57 (10.04–10.97) | 10.02 (9.57–10.33) | 9.66 (8.64–9.82) | |
| AIC | 814.30 | 834.48 | 817.57 | |
| Age-group | ||||
| 18–35 | Mean (95% CI) | 4.88 (4.59–4.99) | 4.03 (3.90–4.33) | 4.83 (4.10–5.11) |
| Median (95% CI) | 4.83 (4.57–4.97) | 3.95 (3.34–4.11) | 4.05 (3.71–4.23) | |
| 95th percentile (95% CI) | 12.58 (10.97–12.78) | 12.21 (11.97–12.54) | 11.66 (10.87–11.81) | |
| AIC | 552.65 | 571.75 | 563.20 | |
| 36–55 | Mean (95% CI) | 4.98 (4.04–5.19) | 3.28 (2.97–3.66) | 4.82 (4.01–4.97) |
| Median (95% CI) | 4.95 (4.39–5.01) | 4.32 (3.91–4.57) | 4.18 (3.98–4.41) | |
| 95th percentile (95% CI) | 12.40 (11.91–12.85) | 10.53 (9.79–10.98) | 10.85 (10.01–11.20) | |
| AIC | 403.67 | 404.04 | 406.17 | |
| >55 | Mean (95% CI) | 4.38 (3.96–4.58) | 3.21 (2.99–3.54) | 4.28 (3.86–3.76) |
| Median (95% CI) | 4.34 (3.96–4.48) | 3.72 (3.19–4.12) | 3.65 (3.01–3.77) | |
| 95th percentile (95% CI) | 11.02 (10.8–11.65) | 9.97 (9.18–10.07) | 9.91 (9.12–10.46) | |
| AIC | 423.25 | 429.62 | 425.25 |
AIC, Akaike Information Criterion; CI, Confidence interval; Unit: days; Period-1: 19 January−19 April 2020 and Period-2: 20 April−16 October 2020.