Effects of interventions on the demand for hospital services in an influenza pandemic: a sensitivity analysis.

Principles: The evaluation of the capacity of a country's public health system in case of an influenza pandemic is essential for preparedness planning. Only few studies compare existing medical resources with those required during a severe pandemic.

Methods: We perform a sensitivity analysis with the freely available simulation tool InfluSim to explore the expected number of outpatient visits and the hospital bed occupancy in an influenza pandemic in Switzerland. We define plausible ranges for unknown parameter values and take random samples from these ranges. A set of four simulations is run for each parameter constellation, considering no intervention, contact reduction, antiviral treatment or a combination of both interventions.

Results: We find that the peak number of outpatient visits of influenza patients would still be manageable by the current number of active physicians with praxis in Switzerland, and that the demand of hospital beds would be only sustainable in the case of a good compliance of the combined interventions. On the other hand, the demand on intensive care unit beds is unsustainably high.

Conclusions: The range of outcomes, resulting from parameter uncertainty, reaches from outpatient and hospitalization values which are half as high as the median to values which double the median. A combination of antiviral treatment and social distancing can considerably mitigate a severe pandemic, but will only bring it under control for the most optimistic parameter constellation combining (mild outbreaks with a high compliance of interventions).