Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, United States.
Department of Civil and Environmental Engineering, Villanova University, PA 19085, United States.
Vaccine. 2023 Aug 7;41(35):5097-5112. doi: 10.1016/j.vaccine.2023.05.056. Epub 2023 May 29.
The B.1.1.529 (Omicron) variant surge has raised concerns about the effectiveness of vaccines and the impact of imprudent reopening. Leveraging over two years of county-level COVID-19 data in the US, this study aims to investigate relationships among vaccination, human mobility, and COVID-19 health outcomes (assessed via case rate and case-fatality rate), controlling for socioeconomic, demographic, racial/ethnic, and partisan factors. A set of cross-sectional models was first fitted to empirically compare disparities in COVID-19 health outcomes before and during the Omicron surge. Then, time-varying mediation analyses were employed to delineate how the effects of vaccine and mobility on COVID-19 health outcomes vary over time. Results showed that vaccine effectiveness against case rate lost significance during the Omicron surge, while its effectiveness against case-fatality rate remained significant throughout the pandemic. We also documented salient structural inequalities in COVID-19-related outcomes, with disadvantaged populations consistently bearing a larger brunt of case and death tolls, regardless of high vaccination rates. Last, findings revealed that mobility presented a significantly positive relationship with case rates during each wave of variant outbreak. Mobility substantially mediated the direct effect from vaccination to case rate, leading to a 10.276 % (95 % CI: 6.257, 14.294) decrease in vaccine effectiveness on average. Altogether, our study implies that sole reliance on vaccination to halt COVID-19 needs to be re-examined. Well-resourced and coordinated efforts to enhance vaccine effectiveness, mitigate health disparity and selectively loosen non-pharmaceutical interventions are essential to bringing the pandemic to an end.
奥密克戎变异株的传播引发了人们对疫苗有效性和鲁莽重新开放的影响的担忧。本研究利用美国两年多的县级 COVID-19 数据，旨在调查疫苗接种、人类流动性与 COVID-19 健康结果（通过发病率和病死率评估）之间的关系，同时控制社会经济、人口统计学、种族/族裔和党派因素。首先拟合了一组横断面模型，以实证比较奥密克戎传播前后 COVID-19 健康结果的差异。然后，采用时变中介分析来描绘疫苗和流动性对 COVID-19 健康结果的影响随时间的变化。结果表明，疫苗对发病率的有效性在奥密克戎传播期间失去了意义，而其对病死率的有效性在整个大流行期间仍然显著。我们还记录了 COVID-19 相关结果中的显著结构性不平等，无论疫苗接种率高，弱势人群始终承担着更大的发病率和死亡率负担。最后，研究结果表明，在变异株爆发的每一波中，流动性与发病率呈显著正相关。流动性大大介导了疫苗接种对发病率的直接效应，导致疫苗对发病率的有效性平均降低了 10.276%（95%CI：6.257, 14.294）。总之，我们的研究表明，仅仅依靠疫苗来阻止 COVID-19 疫情需要重新审视。加强疫苗有效性、减轻健康差异和有选择地放宽非药物干预措施的资源充足和协调一致的努力对于结束大流行至关重要。
