Simulating school closure policies for cost effective pandemic decision making

Abstract

Background: Around the globe, school closures were used sporadically to mitigate the 2009 H1N1 influenza pandemic. However, such closures can detrimentally impact economic and social life.

Methods: Here, we couple a decision analytic approach with a mathematical model of influenza transmission to estimate the impact of school closures in terms of epidemiological and cost effectiveness. Our method assumes that the transmissibility and the severity of the disease are uncertain, and evaluates several closure and reopening strategies that cover a range of thresholds in school-aged prevalence (SAP) and closure durations.

Results: Assuming a willingness to pay per quality adjusted life-year (QALY) threshold equal to the US per capita GDP ($46,000), we found that the cost effectiveness of these strategies is highly dependent on the severity and on a willingness to pay per QALY. For severe pandemics, the preferred strategy couples the earliest closure trigger (0.5% SAP) with the longest duration closure (24 weeks) considered. For milder pandemics, the preferred strategies also involve the earliest closure trigger, but are shorter duration (12 weeks for low transmission rates and variable length for high transmission rates).

Conclusions: These findings highlight the importance of obtaining early estimates of pandemic severity and provide guidance to public health decision-makers for effectively tailoring school closures strategies in response to a newly emergent influenza pandemic.

Figure 1

School closure policy pathway for high transmission scenarios. The full tree for the 0.5% school-age prevalence closure trigger is shown. All other closure triggers have the same decision options as the 0.5% trigger, but are not depicted. The policy option in blue (24-week closure triggered by 0.5% school-aged prevalence) is one of the efficient options in the tree under both high transmission scenarios (high and low severity).

Figure 2

a: Cost and effectiveness comparison of school closure strategies with different closure triggers for low transmission-low CFR scenario. Red circles indicate efficient strategies. b: Cost and effectiveness comparison of school closure strategies with different closure triggers for low transmission-high CFR scenario. Red circles indicate efficient strategies.

Figure 3

a: Cost and effectiveness comparison of school closure strategies with different closure triggers for high transmission-low CFR scenario. Red circles indicate efficient strategies. b: Cost and effectiveness comparison of school closure strategies with different closure triggers for high transmission-high CFR scenario. Red circles indicate efficient strategies.

Figure 4

Total influenza prevalence curves with and without school closures under low transmission (black) and high transmission (blue) scenarios. Dashed lines show a typical epidemic curve under a cost effective closure policy (based on one simulation). Vertical dotted lines indicate beginning and end of each school closure.

Figure 5

Tornado diagram comparing the relative impact of input variables on the ICER for the preferred closure policy (0.5% SAP trigger, 24-week) under the High transmission-High severity scenario. The width of the bars indicates the uncertainty associated with each parameter as it ranges from 50% of its base value to two times of its base value, as given in Additional file 1.