Table 1. Parameters and summary statistics to explain influenza outbreaks with multiple waves.
| Estimated quantity | RAF camps (1918)* | Tristan da Cunha (1971)* |
| R0 = average number of secondary cases from each primary case in a fully susceptible population | 2.88 (2.26, 4.28) | 6.44 (3.73, 10.69) |
| z = proportion susceptible before first wave | 0.51 (0.34, 0.65) | 0.84 (0.62, 0.99) |
| α = proportion of people with latent infections who develop symptoms | 0.38 (0.28, 0.60) | 0.91 (0.72, 1.00) |
| ρ = proportion of infections followed by longer-lasting protection | 0.55 (0.41, 0.70) | 0.49 (0.39, 0.57) |
| 2/φ = Tw = mean time (days) in temporarily resistant state after infection | 68 (56, 95) | 12 (9, 17) |
| 2/γ = Te = mean latent period (days) | 1.30 (fixed) | 1.36 (0.82, 1.87) |
| 1/υ = Ti = mean infective period (days) | 1.00 (fixed) | 0.98 (0.30, 1.83) |
| 2/γ+1/υ = mean serial interval (days) | 2.30 (fixed) | 2.34 (1.56, 3.26) |
| Initial doubling time in fully susceptible population (days) | 1.25 (0.85, 1.69) | 0.62 (0.52, 0.73) |
| Initial doubling time in actual population (days) | 3.93 (3.69, 4.19) | 0.72 (0.63, 0.81) |
| Initial transmissions per day per transmitter in fully susceptible population | 2.88 (2.26, 4.28) | 6.76 (3.84, 16.35) |
| Initial transmissions per day per transmitter in actual population | 1.46 (1.43, 1.50) | 5.59 (3.20, 13.33) |
*
The 1918 pandemic is known to have been caused by H1N1; the 1971 outbreak on Tristan da Cunha was caused by H3N2.
Parameter values (median, 95% credibility intervals) were estimated by MCMC simulation (See Appendix S1). The estimate for the mean serial interval, the mean doubling times and transmissions per day per transmitter were derived from the full MCMC distributions.