No Panic in Pandemic: The Impact of Individual Choice on Public Health Policy and Vaccine Priority

Abstract

Infectious disease outbreaks such as COVID-19 pose significant public health threats and challenges worldwide resulting from their high transmissibility and potentially severe symptoms and complications if infected. Although public health interventions such as social distancing and lockdown can slow the disease spread, the disruption to regular economic and social activities caused by these interventions have caused significant financial losses. Strategic planning is required to optimize the timing and intensity of these public health interventions by considering the public's response. We use a multinomial discrete choice model to characterize individual activity level and integrate it into a repeated game-theoretical model with epidemiological compartmental models capturing disease transmission dynamics. We derive insightful structural properties of the optimal public health interventions and conduct numerical studies based on representative COVID-19 data in Minnesota. We find that the individual equilibrium activity level is higher than the socially optimal activity level due to an individual’s ignorance of the negative externality imposed on others, with the largest difference at a middle-range disease prevalence. As a result, in contrast to the intuition that lockdown policies should be instituted when disease prevalence is at its peak level, we find that lockdowns are more effective when disease prevalence is moderate. Similarly, we find that social distancing policies are more effective when the disease prevalence is not at its peak level. We also find social distancing is more effective than lockdowns based on the representative COVID-19 data from Minnesota. Lastly, we find that the trade-off between higher mortality rate and negative externality imposed by the active age/risk group is the key to determine the best strategy for vaccination priority. Changes in vaccine capacity, mortality rate, and transmission rate result in different vaccination priorities. While the vaccine priority to the elderly group is most effective in reducing total deaths, it has to be accompanied by more strict social distancing policies.