Table 4.
Analysis of the influenza H3N2 epidemic during 1977–1978 and the H1N1 epidemic during 1978–1979 in Seattle. Estimates and 95% CIs (in parentheses) are presented by the infectiousness level of asymptomatic cases relative to symptomatic cases (θ). The hybrid EM-MCEM algorithm with K0 = 200, K = 1000, and J = 500 is used for inference. A tolerance rate of 10−5 for the relative error in every parameter is used to determine convergence during the EM iterations.
| Parameter | 1977–1978, H3N2
|
1978–1979, H1N1†
|
||||
|---|---|---|---|---|---|---|
| θ = 0 | θ = 0.5 | θ = 1 | θ = 0 | θ = 0.5 | θ = 1 | |
| b(×10−4) | 10.66 (7.58,15.0) | 10.12 (7.16,14.29) | 9.86 (6.97,13.94) | 9.11 (7.35,11.30) | 8.77 (7.02,10.96) | 8.79 (7.02,10.99) |
| p(×10−2) | 6.49 (3.99,10.39) | 6.47 (4.08,10.12) | 5.78 (3.70,8.92) | 7.48 (4.40,12.43) | 6.28 (3.74,10.35) | 4.74 (2.76,8.01) |
| φ | 0.81 (0.65,0.91) | 0.62 (0.52,0.70) | ||||
| SAR | 0.27 (0.18,0.40) | 0.27 (0.18,0.39) | 0.25 (0.16,0.36) | 0.31 (0.19,0.46) | 0.27 (0.17,0.40) | 0.21 (0.12,0.32) |
| ORbp,AGE | 0.26 (0.19,0.38) | 0.26 (0.18,0.37) | 0.26 (0.18,0.37) | 0.045 (0.017,0.11) | 0.046 (0.018,0.12) | 0.048 (0.019,0.12) |
| ORbp,TITER | ||||||
| 2 vs 1 | 1.20 (0.80,1.79) | 1.21 (0.81,1.81) | 1.23 (0.82,1.83) | 0.77 (0.53,1.13) | 0.76 (0.52,1.11) | 0.76 (0.52,1.11) |
| 3 vs 1 | 0.51 (0.32,0.82) | 0.50 (0.32,0.81) | 0.50 (0.31,0.80) | 0.093 (0.012,0.70) | 0.091 (0.012,0.68) | 0.090 (0.012,0.68) |
| 4 vs 1 | 0.22 (0.13,0.37) | 0.22 (0.13,0.36) | 0.22 (0.13,0.37) | |||
| ORφ,AGE | 0.55 (0.25,1.19) | 0.41 (0.059,2.92) | ||||
| ORφ,TITER | ||||||
| 2 vs 1 | 0.87 (0.34,2.19) | 2.25 (0.94,5.40) | ||||
| 3 vs 1 | 0.31 (0.11,0.90) | |||||
| 4 vs 1 | 0.39 (0.13,1.22) | |||||
†
Pre-season antibody titer levels 2 and 3 are combined for ORφ,TITER.