Quadrant Health Economics Inc, Cambridge, Canada.
Moderna, Inc, Cambridge, MA, USA.
J Med Econ. 2022 Jan-Dec;25(1):1127-1139. doi: 10.1080/13696998.2022.2126127.
Emerging SARS-COV-2 variants are spurring the development of adapted vaccines as public health authorities plan for fall vaccinations. This study estimated the number of infections and hospitalizations prevented by three potential booster strategies for adults (≥18 years) in the United States: boosting with either Moderna's (1) licensed first generation monovalent vaccine mRNA-1273 (ancestral strain) or (2) candidate bivalent vaccine mRNA-1273.214 (ancestral + BA.1 variant of concern [VOC]) starting in September 2022, or (3) Moderna's updated candidate bivalent vaccine mRNA-1273.222 (ancestral + BA.4/5 VOC) starting November 2022 due to longer development time.
An age-stratified, transmission dynamic, Susceptible-Exposed-Infection-Recovered (SEIR) model, adapted from previous literature, was used to estimate infections over time; the model contains compartments defined by SEIR and vaccination status. A decision tree was used to estimate clinical consequences of infections. Calibration was performed so the model tracks the actual course of the pandemic to present time.
Vaccinating with mRNA-1273(Sept), mRNA-1273.214(Sept), and mRNA-1273.222(Nov) is predicted to reduce infections by 34%, 40%, and 18%, respectively, and hospitalizations by 42%, 48%, and 25%, respectively, over 6 months compared to no booster. Sensitivity analyses around transmissibility, vaccine coverage, masking, and waning illustrate that boosting with mRNA-1273.214 in September prevented more cases of infection and hospitalization than the other vaccines.
With the emergence of new variants, key characteristics of the virus that affect estimates of spread and clinical impact also evolve, making parameter estimation difficult. Our analysis demonstrated that boosting with mRNA-1273.214 was more effective over 6 months in preventing infections and hospitalizations with a BA.4/5 subvariant than the tailored vaccine, simply because it could be deployed 2 months earlier. We conclude that there is no advantage to delay boosting until a more effective BA.4/5 vaccine is available; earlier boosting with mRNA-1273.214 will prevent the most infections and hospitalizations.
随着 SARS-COV-2 新变种的出现，公共卫生部门正在计划秋季接种疫苗，这促使人们开发出了改良疫苗。本研究旨在评估 3 种潜在的成人（≥18 岁）加强针策略在美国的效果：2022 年 9 月开始使用 Moderna 的（1）已授权第一代单价疫苗 mRNA-1273（原始株）或（2）候选二价疫苗 mRNA-1273.214（原始株+关注的变异株 [VOC] BA.1），或（3）由于开发时间较长，2022 年 11 月开始使用 Moderna 的更新候选二价疫苗 mRNA-1273.222（原始株+VOC BA.4/5）。
我们使用了一种年龄分层的、传播动力学的、易感-暴露-感染-恢复（SEIR）模型，该模型改编自之前的文献，用于估计随时间推移的感染情况；该模型包含由 SEIR 和疫苗接种状态定义的隔室。我们使用决策树来估计感染的临床后果。我们进行了校准，以使模型能够跟踪大流行到现在的实际进程。
与不接种加强针相比，接种 mRNA-1273（9 月）、mRNA-1273.214（9 月）和 mRNA-1273.222（11 月）分别预计可减少 34%、40%和 18%的感染，以及分别减少 42%、48%和 25%的住院。关于传染性、疫苗覆盖率、掩蔽和衰减的敏感性分析表明，9 月接种 mRNA-1273.214 比其他疫苗预防更多的感染和住院病例。
随着新变种的出现，影响传播和临床影响估计的病毒关键特征也在演变，这使得参数估计变得困难。我们的分析表明，在预防感染和住院方面，6 个月内接种 mRNA-1273.214 比定制疫苗更有效，这仅仅是因为它可以提前 2 个月部署。我们的结论是，没有优势可以推迟加强针接种，直到更有效的 BA.4/5 疫苗问世；尽早接种 mRNA-1273.214 可以预防更多的感染和住院。
