title: Individual Vaccination as Nash Equilibrium in a SIR Model with Application to the 2009-2010 Influenza A (H1N1) Epidemic in France.
abstract: The vaccination against ongoing epidemics is seldom compulsory but remains one of the most classical means to fight epidemic propagation. However, recent debates concerning the innocuity of vaccines and their risk with respect to the risk of the epidemic itself lead to severe vaccination campaign failures, and new mass behaviors appeared driven by individual self-interest. Prompted by this context, we analyze, in a Susceptible-Infected-Recovered model, whether egocentric individuals can reach an equilibrium with the rest of the society. Using techniques from the "Mean Field Games" theory, we extend previous results and show that an equilibrium exists and characterizes completely the individual best vaccination strategy (with or without discounting). We also compare with a strategy based only on overall societal optimization and exhibit a situation with nonnegative price of anarchy. Finally, we apply the theory to the 2009-2010 Influenza A (H1N1) vaccination campaign in France and hint that a group of individuals stopped vaccinating at levels that indicated a pessimistic perception of the risk of the vaccine.
authors.affiliation: CEREMADE, Université Paris Dauphine, 75016, Paris, France. laguzet@ceremade.dauphine.fr.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Laguzet
authors.affiliation: CEREMADE, Université Paris Dauphine, 75016, Paris, France. Gabriel.Turinici@dauphine.fr.|Institut Universitaire de France, Paris, France. Gabriel.Turinici@dauphine.fr.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Turinici
mesh_terms: D058872:Epidemics / Q000517:prevention & control / Q000706:statistics & numerical data; D005602:France / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000494:pharmacology; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control; D055641:Mathematical Concepts; D008954:Models, Biological
chemical_list: D007252:Influenza Vaccines
keywords: Epidemic control; Individual vaccination; Mean field games; Nash equilibrium; SIR model; Vaccine scares