The age-related dysregulation and decline of the immune system—collectively termed “immunosenescence”—has been generally associated with an increased susceptibility to infectious pathogens and poor vaccine responses in older adults. While numerous studies have reported on the clinical outcomes of infected or vaccinated individuals, our understanding of the mechanisms governing the onset of immunosenescence and its effects on adaptive immunity remains incomplete. Age-dependent differences in T and B lymphocyte populations and functions have been well-defined, yet studies that demonstrate direct associations between immune cell function and clinical outcomes in older individuals are lacking. Despite these knowledge gaps, research has progressed in the development of vaccine and adjuvant formulations tailored for older adults in order to boost protective immunity and overcome immunosenescence. In this review, we will discuss the development of vaccines for older adults in light of our current understanding—or lack thereof—of the aging immune system. We highlight the functional changes that are known to occur in the adaptive immune system with age, followed by a discussion of current, clinically relevant pathogens that disproportionately affect older adults and are the central focus of vaccine research efforts for the aging population. We conclude with an outlook on personalized vaccine development for older adults and areas in need of further study in order to improve our fundamental understanding of adaptive immunosenescence.

中文翻译：

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免疫衰老和人类疫苗免疫反应

与年龄相关的免疫系统失调和衰退（统称为“免疫衰老”）通常与老年人对传染性病原体的易感性增加和疫苗反应差有关。虽然许多研究报告了受感染或接种疫苗的个体的临床结果，但我们对控制免疫衰老发生的机制及其对适应性免疫的影响的理解仍然不完整。T 和 B 淋巴细胞群和功能的年龄依赖性差异已得到明确定义，但缺乏证明免疫细胞功能与老年人临床结果之间直接关联的研究。尽管存在这些知识差距，在为老年人量身定制的疫苗和佐剂配方的开发方面取得了进展，以增强保护性免疫力并克服免疫衰老。在这篇综述中，我们将根据我们目前对衰老免疫系统的了解（或缺乏了解）来讨论针对老年人的疫苗开发。我们重点介绍已知的适应性免疫系统随着年龄的增长而发生的功能变化，然后讨论当前与临床相关的病原体，这些病原体对老年人的影响不成比例，并且是针对老年人群的疫苗研究工作的中心焦点。最后，我们展望了针对老年人的个性化疫苗开发和需要进一步研究的领域，以提高我们对适应性免疫衰老的基本理解。