Cost-effectiveness of Ward Closure to Control Outbreaks of Norovirus Infection in United Kingdom National Health Service Hospitals

Background. Norovirus is the most common cause of outbreaks of acute gastroenteritis in National Health Service hospitals in the United Kingdom. Wards (units) are often closed to new admissions to stop the spread of the virus, but there is limited evidence describing the cost-effectiveness of ward closure. Methods. An economic analysis based on the results from a large, prospective, active-surveillance study of gastroenteritis outbreaks in hospitals and from an epidemic simulation study compared alternative ward closure options evaluated at different time points since first infection, assuming different efficacies of ward closure. Results. A total of 232 gastroenteritis outbreaks occurring in 14 hospitals over a 1-year period were analyzed. The risk of a new outbreak in a hospital is significantly associated with the number of admission, general medical, and long-stay wards that are concurrently affected but is less affected by the level of community transmission. Ward closure leads to higher costs but reduces the number of new outbreaks by 6%-56% and the number of clinical cases by 1%-55%, depending on the efficacy of the intervention. The incremental cost per outbreak averted varies from £10 000 ($14 000) to £306 000 ($428 000), and the cost per case averted varies from £500 ($700) to £61 000 ($85 000). The cost-effectiveness of ward closure decreases as the efficacy of the intervention increases, and the cost-effectiveness increases with the timing of the intervention. The efficacy of ward closure is critical from a cost-effectiveness perspective. Conclusions. Ward closure may be cost-effective, particularly if targeted to high-throughput units.