Modeling vaccine allocation and equity implications of COVID-19 containment strategies

Given the shortage of global COVID-19 vaccines, a critical public concern is whether the strategy of allocation exerts a heterogeneous effect on settings that have imbalanced accessibility. Exacerbated by the mutational characteristics of the pathogen, traits of immunity protection of vaccines, and diversification of human behaviors, the pathway to the full eradication of the COVID-19 pandemic is becoming increasingly complicated and indeterminate. Population-wide evaluation of public interventions remains crucial to evaluate the performance of epidemiology policies. This study employs a mathematical compartmental model combined with the observational data of the United States to examine the potential effect of vaccine allocation on the trajectory of COVID-19 transmission and the elicited equity implications. The outcomes imply that allocation strategies substantially impact the cumulative equilibrium size of a pandemic controlling for confounding factors. Under a framework of a two-dose primary vaccination strategy aiming to curb the total infections for high-accessibility settings (HAS) and low-accessibility settings(LAS), the traits of vaccination, pathogen, and human effort integrally affect the equilibrium of the COVID-19 pandemic in the medium perspective (i.e., up to 5 years). Vaccine allocation increases the healthcare and cost burden for HAS temporarily, in contrast, it reduces the risk of COVID-19 transmission for the LAS. The effects are consistent across a variety of profiles. By enhancing the administration rates of primary doses (i.e., mainly through dose 1 and dose 2), the magnitude of the COVID-19 pandemic decreases contingent on confounding factors. To minimize the magnitude of infection, it is of importance to dynamically monitor the immunity protection of vaccines, the dynamics of virus transmission, and the gap in the human effort.