Managing Two-Dose COVID-19 Vaccine Rollouts with Limited Supply : Operations Strategies for Distributing Time-Sensitive Resources

Distributing scarce resources such as COVID-19 vaccines is often a highly time-sensitive and mission-critical operation. On top of that, most COVID-19 vaccines require two doses to be administered three or four weeks apart. How to effectively roll out two-dose vaccines is a crucial policy decision given that many countries are struggling with limited supply and facing mounting pressure to slash hospitalizations and mortality and to rapidly achieve herd immunity through vaccination. In this paper, we first model and analyze inventory dynamics of the rollout process under three rollout strategies: (1) holding back second doses, (2) releasing second doses, and (3) stretching the lead time between doses. Then we develop an SEIR model that incorporates COVID-19 asymptomatic and symptomatic infections to evaluate these strategies in terms of infections, hospitalizations, and mortality.Among our findings, we show releasing second doses reduces infections but creates uneven vaccination patterns. In addition, to ensure second doses are given on time without holding back inventory, strictly less than half of supply can be allocated to first-dose appointments. Stretching the between-dose lead time flattens the infection curve and reduces both hospitalizations and mortality compared with the strategy of releasing second doses. We also consider an alternative single-dose vaccine with a lower efficacy and show the vaccine can be more effective than its two-dose counterparts in reducing infections and mortality. We conduct extensive sensitivity analyses related to age composition, risk-based prioritization, supply disruptions, and disease transmissibility. At a time when many countries, especially in the developing world, face stringent vaccine supply constraints, our research provides important implications for policymakers to develop effective vaccine rollout strategies. More broadly, our paper sheds light on how to develop effective operations strategies for distributing time-sensitive resources in times of crises