Coase-Sandor Working Paper Series in Law and Economics

Immunity Passports and Moral Hazard

Daniel Hemel
Anup Malani


The idea of using “immunity passports” to restart the economy before the arrival of a SARS-CoV-2 vaccine has attracted increasing attention as the Covid-19 crisis has escalated. Under an “immunity passport” regime, individuals who test positive for SARS-CoV-2 antibodies would receive certificates allowing them to return to work and potentially to participate in a broader range of activities without social distancing. One concern raised by the “immunity passport” proposal is that not-yet-infected individuals would have an incentive to expose themselves to the virus intentionally so that they can develop antibodies and obtain passports. This paper evaluates the moral-hazard risk that an immunity passport regime would generate. We develop a rudimentary rational-actor model of self-infection decisions under an immunity passport regime and then parameterize the model using early data on SARS-CoV-2 infection outcomes. Our topline result is that strategic self-infection would be privately rational for younger adults under a wide range of plausible parameters. This result raises two significant concerns. First, in the process of infecting themselves, younger adults may expose others—including older and/or immunocompromised individuals—to SARS-CoV-2, generating significant negative externalities. Second, even if younger adults can self-infect without exposing others to risk, large numbers of self-infections over a short timeframe after introduction of the immunity passport regime may impose significant congestion externalities on health care infrastructure. We then evaluate several interventions that could mitigate moral hazard under an immunity passport regime, including the extension of unemployment benefits, staggered implementation of passports, and controlled exposure of individuals who seek to self-infect. Our results underscore the importance of careful planning around moral hazard as part of any widescale immunity passport regime.