Cost-effectiveness analysis of Vaccination and Self-isolation in case of an H1N1 outbreak

Abstract

In this research, we have conducted a cost-effectiveness analysis to examine the relative importance of vaccination and self-isolation, two common measures for controlling the spread of infectious diseases, with respect to the current H1N1 outbreak. We have developed a continuous-time simulation model for the spread of H1N1 which allows for three types of interventions: antiviral prophylaxis and treatment, vaccination, and self-isolation and mandatory quarantine. We have used the North Carolina State University undergraduate students as our target population. We have developed an optimization model with two decision variables: vaccination fraction and self-isolation fraction among infectives. By considering the relative marginal costs associated with each of these decision variables, we have a linear objective function representing the total relative cost for each control policy. We have also considered upper bound constraints for two of the most critical performance measures: maximum number of individuals under treatment (which is related to surge capacity), and percentage of infected individuals. We used grid search to obtain insight into the model, find the feasible region, and conduct the cost-effectiveness analysis. Then we integrated the simulation and optimization models via the Arena optimization toolbox, OptQuest, to find “near optimal†feasible solutions. Using the estimated model parameters from the target population and literature, our results show that in low levels of interventions, vaccination is more effective and also incrementally cost-effective in controlling the disease spread than self-isolation. While vaccination decreases the number of both susceptibles and infectives (with a delay), self-isolation only affects the number of infectives. On the other hand, in high levels of interventions, self-isolation is more effective and also incrementally cost-effective than vaccination, due to the delay in the vaccine effectiveness and also the incapability of distinguishing between the susceptible and exposed individuals to receive the vaccine. Also our results show that self-isolation is incrementally more cost-effective than vaccination if the ratio of the vaccination marginal cost to the self-isolation marginal cost is greater than 0.3, which should be the case for our target population. To validate the model and to have a realistic estimate of the model parameters, we have taken advantage of the cooperation of the NCSU Health Center Director as an expert. Finally we have conducted a sensitivity analysis on the key input parameters to ensure robust results and conclusions.