Given vaccine dose shortages and logistical challenges, various deployment strategies are being proposed to increase population immunity levels to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Two critical issues arise: How timing of delivery of the second dose will affect infection dynamics and how it will affect prospects for the evolution of viral immune escape via a buildup of partially immune individuals. Both hinge on the robustness of the immune response elicited by a single dose as compared with natural and two-dose immunity. Building on an existing immuno-epidemiological model, we find that in the short term, focusing on one dose generally decreases infections, but that longer-term outcomes depend on this relative immune robustness. We then explore three scenarios of selection and find that a one-dose policy may increase the potential for antigenic evolution under certain conditions of partial population immunity. We highlight the critical need to test viral loads and quantify immune responses after one vaccine dose and to ramp up vaccination efforts globally.

鉴于疫苗剂量短缺和后勤挑战，人们提出了各种部署策略，以提高人群对严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 的免疫力水平。出现了两个关键问题：第二剂的给药时间将如何影响感染动态，以及它将如何通过部分免疫个体的积累影响病毒免疫逃逸进化的前景。与自然免疫和双剂量免疫相比，两者都取决于单剂量引发的免疫反应的稳健性。在现有免疫流行病学模型的基础上，我们发现在短期内，专注于一个剂量通常会减少感染，但长期结果取决于这种相对的免疫稳健性。然后，我们探索了三种选择方案，发现在部分群体免疫的某些条件下，单剂量策略可能会增加抗原进化的潜力。我们强调迫切需要在接种一剂疫苗后测试病毒载量和量化免疫反应，并在全球范围内加大疫苗接种力度。