Does prioritization of COVID vaccine distribution to communities with the highest COVID burden reduce health inequity?

Background: Communities hardest-hit by early SARS-CoV-2 outbreaks accrued more immunity, but prioritizing these communities for vaccination could reduce health disparities. Optimal vaccine allocation depends on inequality aversion, i.e., willingness to trade off aggregate health benefits to increase distributional equity. We evaluated the impact of vaccine prioritization strategies on COVID-19 infections and mortality in New York City (NYC).

Methods: We used a susceptible-exposed-infected-recovered COVID-19 transmission model calibrated to NYC neighborhood-level data to compare three vaccine distribution strategies: 1) uniform across neighborhoods (no prioritization); 2) prioritizing hardest-hit neighborhoods (exposure-based prioritization); and 3) prioritizing hardest-hit neighborhoods while maintaining mitigation measures in other neighborhoods (exposure-based prioritization plus mitigation). The model accounted for vaccine efficacy, rollout pace, pre-vaccine immunity, and heterogeneous neighborhood exposure risk. We categorized 42 NYC neighborhoods into quintiles of cumulative COVID-19 mortality rates from March 1, 2020, until first vaccine availability (December 14, 2020). We modeled total deaths and equally-distributed-equivalent (EDE) deaths (i.e., the equally preferred number of deaths, considering equity and efficiency) across a range of inequality aversion (Atkinson's index, ε=0-20).

Results: Exposure-based prioritization plus mitigation was estimated to avert the most citywide COVID-19 deaths (32.5 %) relative to no vaccination, regardless of adjustment for inequality aversion. Relative to no prioritization, exposure-based prioritization was estimated to avert 45 % fewer citywide deaths but generated 2.5 % more EDE-adjusted deaths at an Atkinson index of 10. Exposure-based prioritization outperformed no prioritization at an Atkinson index of ≥ 6.

Conclusions: Prioritizing vaccination within the hardest-hit communities, paired with sustained mitigation efforts in communities with the greatest advantage, resulted in the greatest overall reduction in mortality and inequities. Emergency response teams should consider a community's ability to continue non-pharmaceutical mitigation efforts when allocating limited pharmaceutical supplies.