Table V.
Model Inputs for the Outbreak Model for the Netherlands
| Model input (symbol) | Best estimate | Source | Notes |
|---|---|---|---|
|
| |||
| Number of subpopulations | 2 | 13,79 | Subpopulation 1: orthodox reformed communities (1/50th of total Dutch population); subpopulation 2: general population (49/50th of total Dutch population) |
| Number of age groups | 12 | 0–2; 3–4; 5–11 months; 1–4; 5–9; 10–14; 15–19; 20–24*; 25–29*; 30–34*; 35–39*; ≥ 40 years | |
| Number of mixing age groups | 4 | 0–4; 5–14; 15–39; ≥ 40 years | |
| Year when model run-up starts | 1903 | Fitted to time peak WPV3 year before IPV introduction | |
| Year when R0 seasonality starts | 1920 | ||
| Year when die-out first allowed | 1950 | Circulation can continue after initial die-out due to assumed annual virus reintroductions | |
| Average basic reproductive number (R0) (PV3) | 4 | Fitted within range for highest tier (Table III) | |
| Proportional change in R0 due to seasonality (α) | 0.35 | 13 | Significant seasonality based on model calibration to contribute to natural die-out and observed outbreak kinetics |
| Day of seasonal peak in R(pd) | 270 (September 27) | 13 | Fitted within previously assumed range |
| Proportion of contacts reserved for individuals within the same mixing age group () | 0.4 | For simplicity, assume equal values for each mixing age group | |
| Proportion of potentially infectious contacts of individuals in subpopulation 1 that are with individuals in subpopulation 1 (pwithin) | 0.99 | 13 | Force of infection as a result of mixing between subpopulations modeled using previously described approach(13) (see Appendix A1) |
| Characterization of regular WPV importations | Assume WPV importations reduced significantly after national control of WPV, with no significant WPV3 spread in the population since 1960 | ||
| - Frequency | Annual | ||
| -Day of introductions | 91 (April 1) | ||
| - First year without introductions | 1960 | ||
| Proportion of transmissions via oropharyngeal route () | 0.95 | 19 | Fitted within range of expert assessments(19) |
| Per-dose take rate (tr) (PV3) | Fitted within range for highest tier (Table III); IPV take rates based loosely on field efficacy of IPV against poliomyelitis in the USA in 1954;(55) better take rates after 1965(80) due to enhanced vaccine and known high seroconversion(6,41) | ||
| - IPV (Salk), 1957–1964 | 0.5a | ||
| - Improved IPV or eIPV, 1965–1994 | 0.9b | ||
| - tOPV | 0.55c | ||
| Assumptions about IPV campaigns 1957–1959 | 79,80 | Take rates based on field efficacy of IPV against type 1 poliomyelitis in the USA in 1954; assume catch-up campaigns target people born 1945–1957 and achieved ∼ 90% coverage(79,80) | |
| - Average cumulative number of doses per covered child aged up to 14 years | 3.0 | ||
| - Cumulative coverage of IPV campaigns | 0.9 | ||
| Nationwide coverage with recommended doses by age 1 | 76,79,80 | ||
| - Before 1963 | 0.9 | ||
| - 1963 | 0.92 | ||
| - 1964–1966 | 0.94 | ||
| - 1967–1974 | 0.95 | ||
| -1975–1994 | 0.97 | ||
| Coverage compared to national average | 13 | ||
| - Subpopulation 1, IPV campaigns 1957–1959 | 0.5 | ||
| - Subpopulation 1, routine IPV 1960–1992 | 0.2 | ||
| - Subpopulation 2 | 1.0 | ||
| Characterization of routine IPV immunization | 79,80 | Assume negligible effect of partial coverage of primary schedule given high coverage of complete schedule | |
| - Primary doses by age 3 months | 3 | ||
| - Primary doses at 12 months | 1 | ||
| - Coverage with 0, 1, 2, or 3 primary doses given < 4 doses by age 12 months | 0 | ||
| - Booster dose at ages (years) | 5,10 | ||
| - Relative coverage of booster vs. primary doses | 1.0 | ||
| Date of introduction for the 1992–1993 outbreak | July 18, 1992 | 13 | Fitted value within previously characterized range |
| Characterization of outbreak response, 1992 | 13 | Similar assumptions as in prior work(13) | |
| - First day of response (1992) | 266 (September 22) | ||
| - Duration of response (days) | 365 | ||
| - Average tOPV doses per covered person in subpopulation 1 | 3 | ||
| - Average eIPV doses per covered person in subpopulation 1 | 2 | ||
| - Coverage in subpopulation 1 | 0.30 | ||
| - Coverage in subpopulation 2 | 0.50 | ||
Acronyms: eIPV = enhanced-potency IPV; IPV = inactivated poliovirus vaccine; PV3 = poliovirus type 3; tOPV = trivalent oral poliovirus vaccine; USA = United States of America; WPV(3) = wild poliovirus (type 3)
*
Age groups marked with an asterisk indicate age groups that count towards determining the fraction of newborns who receive maternal antibodies, based on the immune fraction in those age groups (see Appendix A1).
a
For runs to verify behavior of other serotypes, we use take rates for IPV (Salk) of 0.5 and 0.6 for type 1 and 2, respectively.
b
For runs to verify behavior of other serotypes, we use take rates for eIPV of 0.9 for all types.
c
For runs to verify behavior of other serotypes, we use take rates for tOPV of 0.65 and 0.75 for type 1 and 2, respectively.