Volume 13, Number 3—March 2007
Research
Effectiveness of Neuraminidase Inhibitors for Preventing Staff Absenteeism during Pandemic Influenza
Vernon J. Lee*
and Mark I. Chen*
and Mark I. Chen*Table 1
Parameters of neuraminadase inhibitor stockpiling strategies model*
| Parameter | Notation† | Minimum‡ | Base case‡ | Maximum‡ | Reference |
|---|---|---|---|---|---|
| Input | |||||
| General population | Ng | 4,350,000 | (13) | ||
| Healthcare staff | Nh | 20,000 | Estimated | ||
| ILI rate, per day | ι | 2,800 | (2) | ||
| Transmission dynamics | |||||
| Incubation and latent period, d | α | 1.0 | 2.0 | 3.0 | (9,10) |
| Infectious period, d | γ | 1.5 | 4.1 | 7.0 | (9,10) |
| Reproductive number | R0 | 1.5 | 2.5 | 6.0 | (9,14) |
| Transmission probability/d | β | 0.37 | 0.61 | 2.0 | Calculated, R/γ |
| HCW-to-HCW transmission | ω | 0.2 | 0.5 | 0.8 | See text |
| HCW infections caused by incident cases of clinical influenza (H/P) | δ | 0 | 2.0 | See text | |
| Detection threshold, proportion of baseline ILI rate | ν | Introduction of 1st case | 0.1 | 1 | See text |
| Disease severity and antiviral efficacy | |||||
| Hospitalization rate (HCW)/100,000 infected§ | η | 12.4 | 88.6 | 186.7 | (2) |
| Length of stay and medical leave if hospitalized, d | φ | 9.0 | 12.0 | 20.0 | (2) |
| Case-fatality rate (HCW)/100,000 infected§ | μ | 1.9 | 20.3 | 65.1 | (2) |
| Proportion of infected persons without prophylaxis who have symptoms | θ1 | 0.50 | 0.67 | 0.80 | (9,15) |
| Oseltamivir efficacy for preventing infection in exposed persons | ε1 | 0.28 | 0.35 | 0.52 | (9,16,17) |
| Oseltamivir efficacy for preventing disease in infected persons | ε2 | 0.5 | 0.6 | 0.9 | (2,9) |
| Oseltamivir efficacy for preventing transmission of infection by infected persons | ε3 | 0.6 | 0.8 | 0.98 | (9) |
| Proportion of infected persons receiving oseltamivir prophylaxis who have symptoms | θ2 | 0.07 | - | 0.2 | Calculated, θ2 = θ1(1−ε2) |
| Medical leave without treatment, d | σ | 2 | 4 | 5 | (2) |
| Reduction in medical leave with oseltamivir treatment, d | χ | 0.1 | 1.0 | 2.0 | (2) |
| Reduction in hospitalization or case-fatality rate with treatment | ψ | 0.4 | 0.6 | 0.8 | (2,18) |
*HCW, healthcare workers, ILI, influenzalike illness.
†Notations are used in the equations listed in the Appendix.
‡Base case values are given with the minimum and maximum values used in the model where applicable.
§Based on hospitalizations and deaths among those with clinical influenza.
