Table 6 Parameter estimates for the ongoing outbreak in West Africa
Parameter | All countries * | Guinea | Liberia | Nigeria | Sierra Leone | References |
|---|---|---|---|---|---|---|
Incubation Period Distribution (days) | ||||||
 Multi-day exposures, observed (mean) | 11.4, n=155 | 10.9, n=20 | 11.7, n=79 | — | 10.8, n=48 | |
 Single-day exposures, observed, (median (IQR)) | 9 (5–13) |  |  |  |  | |
 Fitted single-day exposures (mean, (95% CI)) | 10.3 (9.9, 10.7) |  |  |  |  | |
 Fitted values (mean) |  |  | 12 |  | 10 | |
Serial interval Distribution (days) | ||||||
 WHO ERT 2014 (gamma fit mean, s.d., n) | 15.3, 9.3, n=92) | 19.0, 11.2, n=40) | 13.1, 7.8, n=26) | — | 11.6, 6.3, n=25) | |
 WHO ERT 2015 (gamma fit mean, (95% CI), n) | 14.2 (13.1, 15.3), n=305 |  |  |  |  | |
 Fisman et al.30 | 15 days (derived) |  |  |  |  | |
 Faye et al. 2014 (mean, (range), s.d., (95% CI for s.d.)) |  | 14.2 (13.1–15.5), 7.1 (6.2, 8.2) |  |  |  | |
R 0 (estimate, (95% CI)) | ||||||
 With estimated serial interval 15.3 d | — | 1.71 (1.44, 2.01) | 1.83 (1.72, 1.94) |  | 2.02 (1.79, 2.26) | |
 With fixed incubation period 5.3 d | — | 1.51 (1.50, 1.52) | 1.59 (1.57, 1.60) | 9.0 (5.2, 15.6) †| 2.53 (2.41, 2.67) | |
 Overall, data driven | 1.8 (1.5, 2.0) | — | — | — | — | |
 SEIR model | 2.1 (1.9, 2.4) | — | — | — | — | |
 Community using Legrand et al.59 model | 0.8 (0.3, 0.9) | — | — | — | — | |
 Hospital using Legrand et al.59 model | 0.4 (0.2, 1.4) | — | — | — | — | |
 Funeral using Legrand et al.59 model | 0.6 (0.2, 1.0) | — | — | — | — | |
 Assumed fixed generation time of 15d | 1.78 | 2.46 | 1.72 | — | 8.33 | |
 Estimated mean serial interval 15.3d | — | 1.71 (1.44, 2.01) | 1.83 (1.72, 1.94) | 1.2 (0.67, 1.96) | 2.02 (1.79, 2.26) | |
 Overall (Conakry) |  | 1.7 (1.2, 2.3) |  |  |  | |
 Community (Conakry) |  | 1.0 (0.6, 1.5) |  |  |  | |
 Hospital (Conakry) |  | 0.4 (0.2, 0.7) |  |  |  | |
 Funeral (Conakry) |  | 0.3 (0.1, 0.6) |  |  |  | |
 Montserrado only |  |  | 2.49 (2.38, 2.60) |  |  | |
 Webb et al. 2015 |  |  | 1.54 |  | 1.26 | |
 Rivers et al.48 (overall) |  |  | 2.22 |  | 1.78 | |
 Rivers et al.48 (community) |  |  | 1,35 |  | 1.11 | |
 Rivers et al.48 (hospitals) |  |  | 0.35 |  | 0.24 | |
 Rivers et al.48 (funerals) |  |  | 0.53 |  | 0.43 | |
 Khan et al.63 (raw data) |  |  | 1.76 |  | 1.49 | |
 Khan et al.63 (corrected for underreporting) |  |  | 1.9 |  | 1.37 | |
R t (estimate, (95% CI)) | ||||||
 Estimated mean serial interval 15.3 d | — | 1.81 (1.60, 2.03) | 1.51 (1.41, 1.60) | <1†| 1.38 (1.27, 1.51) | |
 Estimated mean generation time 12 d‡ | — | 1 | 1.7 | — | 1.4 | |
 Sierra Leone (56 days of data) |  |  |  |  | 1.1 (0.95, 1.24) | |
 Montserrado only |  |  | 1.73 (1.66, 1.83) |  |  | |
 Survivors Montserrado only |  |  | 0.66 (0.10, 1.69) |  |  | |
 Non-survivors Montserrado only |  |  | 2.36 (1.72, 2.80) |  |  | |
Observed Delay Distributions (days) | ||||||
 Symptom onset to… | ||||||
… hospitalization | ||||||
 WHO ERT 2014 (mean, s.d., n) | 5.0, 4.7, n=1135 | 5.3, 4.3, n=484 | 4.9, 5.1, n=245 | 4.1, 1.4, n=11 | 4.6, 5.1, n=395 | |
 WHO ERT 2015 (mean, (95% CI), n) | 5.0 (4.9, 5.1), n=5616 |  |  |  |  | |
 Faye et al. 2014 (mean, s.d., n) |  | 5.0, 3.9, n=152 |  |  |  |  |
 Rivers et al.48 (mean) |  |  | 3.24 |  | 4.12 | |
... hospital discharge | ||||||
 WHO ERT 2014 (mean, s.d., n) | 16.4, 6.5, n=267 | 16.3, 6.1, n=152 | 15.4, 8.2, n=41 | — | 17.2, 6.2, n=70 | |
 WHO ERT 2015 (mean, (95% CI)) | 15.1 (14.6, 15.6) |  |  |  |  | |
… death | ||||||
 WHO ERT 2014 (mean, s.d., n) | 7.5, 6.8, n=594 | 6.4, 5.3, n=248 | 7.9, 8, n=212 | — | 8.6, 6.9, n=128 | |
 WHO ERT 2015 (mean, (95% CI)) | 8.2 (7.9, 8.4) |  |  |  |  | |
 Faye et al. 2014 (mean, s.d., n) |  | 8.9, 4.0, n=82) |  |  |  | |
 Althaus et al.61 (mean, range) |  |  |  | 7.41 (4–17), n=17 |  | |
… WHO notification | 6.1, 8.5, n=2185 | 7.5, 10.4, n=743 | 6, 8.7, n=797 | — | 4.5, 5, n=634 | |
WHO notification to… | ||||||
 … hospital discharge (mean, s.d., n) | 11.8, 7.2, n=312 | 11.1, 5.8, n=164 | 11, 8, n=41 | — | 12.7, 8.4, n=102 | |
… death (mean, s.d., n) | -3.0, 13.8, n=584 | -4.4, 14.4, n=300 | -1.8, 13.6, n=221 | — | -1.6, 9.2, n=58 | |
Hospitalization to… | ||||||
 … discharge | ||||||
WHO ERT 2014 (mean, s.d., n) | 11.8, 6.1, n=290 | 11, 5.4, n=159 | 12.8, 8.1, n=40 | — | 12.4, 5.8, n=86 | |
WHO ERT 2015 (mean, (95% CI)) | 11.2 (10.8, 11.7) | Â | Â | Â | Â | |
Rivers et al. 48 (recovery) (mean) | Â | Â | 15.88 | Â | 15.88 | |
 … death | ||||||
WHO ERT 2014 (mean, s.d., n) | 4.2, 6.4, n=121 | 2.5, 3.4, n=36 | 4.5, 6, n=63 | — | 4.4, 6, n=17 | |
WHO ERT 2015 (mean, (95% CI)) | 4.3 (4.1, 4.5) | Â | Â | Â | Â | |
Rivers et al. 48 (mean) | Â | Â | 10.07 | Â | 6.26 | |
Infectious period | ||||||
 Rivers et al.48 (mean) |  |  | 15.00 |  | 18.00 | |
Infection to death | ||||||
 Rivers et al.48 (mean) |  |  | 13.31 |  | 10.38 | |
Case Fatality Rate (estimate, (95% CI), n) | ||||||
 WHO ERT 2014 (based on current status) | 37.7 (36.1, 39.2), n=3747 | 57.5 (53.7, 61.1), n=677 | 34.7 (32.4, 37.1), n=1616 | 40.0 (19.8–64.3), n=15 | 31.6 (29.3, 34.1), n=1439 | |
 Althaus36 (based on reported deaths) |  | 74 (72, 75), n=607 | 71 (69, 74), n=1082 |  | 48 (47, 50), n=910 | |
All cases (based on definitive outcome) | ||||||
 WHO ERT 2014 | 70.8 (68.6, 72.8), n=1737 | 70.7 (66.7, 74.3), n=542 | 72.3 (68.9, 75.4), n=739 | 45.5 (21.3, 72), n=11 | 69.0 (64.5, 73.1), n=445 | |
 WHO ERT 2015 | 70.4 (69.2, 71.6), n=5616 |  |  |  |  | |
 Althaus et al.61 |  |  |  | 39 (14, 71), n=20 |  | |
 Fasina et al.54 |  |  |  | 40 (22, 61), n=20 |  | |
All hospitalized cases | ||||||
 WHO ERT 2014 (based on definitive outcome) | 63.5 (60.5, 66.3), n=1100 | 63.4 (58.6, 67.9), n=434 | 66.6 (61.3, 71.6), n=338 | 100 (2.5, 100), n=1 | 61 (55.4, 66.4), n=318 | |
 WHO ERT 2015 (based on definitive outcome) | 60.7 (59.2, 62.3), n=3839 |  |  |  |  | |
 Rivers et al.48 |  |  | 0.500 |  | 0.750 | |
Subset of Cases | ||||||
 Faye et al. 2014 (Conakry) |  | 54 (49, 63), n=152 |  |  |  | |
