De Donder, PhilippeLlavador, HumbertoPenczynski, StefanRoemer, John E.Vélez-Grajales, Roberto2025-06-032025-06-032025De Donder P, Llavador H, Penczynski SP, Roemer JE, Vélez-Grajales R. Nash versus Kant: a game-theoretic analysis of childhood vaccination behavior. J Econ. 2025;145(2):97-128. DOI: 10.1007/s00712-025-00898-x0931-8658http://hdl.handle.net/10230/70601The vaccination game exhibits positive externalities. The standard game-theoretic approach assumes that parents make decisions according to the Nash protocol, which is individualistic and non-cooperative. However, in more solidaristic societies, parents may behave cooperatively, optimizing according to the Kantian protocol, in which the equilibrium is efficient. We develop a random utility model of vaccination behavior and prove that the equilibrium coverage rate is larger with the Kant protocol than with the Nash one. Using survey data collected from six countries, we calibrate the parameters of the vaccination game, compute both Nash equilibrium and Kantian equilibrium profiles, and compare them with observed vaccination behavior. We find evidence that parents demonstrate cooperative behavior in all six countries. The study highlights the importance of cooperation in shaping vaccination behavior and underscores the need to consider these factors in public health interventions.application/pdfcatThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article¿s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article¿s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.info:eu-repo/semantics/article2025-06-03http://dx.doi.org/10.1007/s00712-025-00898-xKantian equilibriumNash equilibriumMeasles vaccinationFreerider probleminfo:eu-repo/semantics/openAccess