Table 1.
Parameter values for the different pertussis immunity durations considered in this study
| Duration of pertussis immunity | tN | tV | 1/σ | 1/τ | 1/τ′ | 1/σ0 |
|---|---|---|---|---|---|---|
| Short duration immunity (SDI) | 8 | 4 | 5 | 1 | 1·5 | 100 |
| Medium duration immunity (MDI) | 15 | 6 | 11 | 2 | 2 | 100 |
| Long duration immunity (LDI) | 20 | 10 | 14 | 4 | 3 | 100 |
tN and tV are the duration of immunity acquired naturally (through infection) or artificially (through vaccination), respectively. The rates σ, τ and τ′ are chosen to obtain tN = 1/σ + 2/τ′, tV = 1/τ + 2/τ′. The rate at which immunized individuals become completely susceptible is controlled by the slow rate, σ0. All the values in the table are in years.