Table 2.
Model parameters
| Parameters | Base case | Range | Sources |
|---|---|---|---|
| Duration of latent period | 1 day | N/A | Carrat et al.16 |
| Duration of viral shedding | 4·8 days | N/A | Carrat et al.16 |
| Proportion of symptomatic infection | 66·9% | N/A | Carrat et al.16 |
| Duration of natural immunity against influenza A | 6 years* | 1–12 years | Vynnycky et al.17 |
| Duration of natural immunity against influenza B | 12 years* | 6–18 years | Vynnycky et al.17 |
| Duration of vaccine-induced immunity | 1 year* | N/A | Vynnycky et al.17 |
| Vaccine-induced cross-protection | 70% of VE | 0–75% | DiazGranados et al.2 |
| Naturally acquired cross-protection | 50% | N/A | Assumption |
| VE (matched B strain) by age group | |||
| 6–23 months | 61·0% | ±20% | CDC, unpublished data |
| 2–4 years | 61·0% | ||
| 5–10 years | 56·8% | ||
| 11–14 years | 49·2% | ||
| 15–18 years | 49·2% | ||
| 19–49 years | 50·0% | ||
| 50–64 years | 80·0% | ||
| ≥65 years | 60·0% | ||
| R0 A/H1N1 | 1·02–1·76 | N/A | Estimated |
| R0 A/H3N2 | 1·11–2·14 | ||
| R0 B/Victoria | 1·10–1·77 | ||
| R0 B/Yamagata | 1·02–1·86 | ||
CDC, US Centers for Disease Control and Prevention; VE, vaccine efficacy.
*
With exponential decay.