The COVID-19 pandemic strongly impacts the whole world in various dimensions (Wang, 2020), and studies have shown the high mortality risk of older patients with COVID-19 infections (Mostaza, et al., 2020; Niu, et al., 2020). Older age, geriatric syndromes, underlying chronic conditions and multimorbidity have been recognized as major determinants for adverse outcomes of older adults with various clinical conditions, and COVID-19 was no exception (Lim et al., 2020)(). Although the mortality risk of SARS-CoV-2 infections in older people has been reported, older people are not simply an age-defined entity with identical health characteristics (Hajek & König, et al., 2020; Lee, et al., 2020; Liu, et al., 2020). Instead, advancing age substantially increased the variation of health characteristics of older people in their late life (Duim & Lima Passos, 2020; Jeon, 2020). Studies have shown that functional impairment or disability was more important than multimorbidity in predicting their quality of life and mortality (Pivetta, et al., 2020; Li, et al., 2021), which may be applied to COVID-19 pandemic as well. Dumitrascu, et al., conducted a meta-analysis of 118,373 older COVID-19 patients and identified the importance of frailty in predicting mortality and delirium (Dumitrascu, er al., 2021), but not older age alone. Moreover, vulnerable populations like home-bound older persons were at greater mortality risk during the COVID-19 pandemic, but COVID-19 was not the sole cause (Nilsson, et al., 2021). The prevalence of geriatric syndromes and their impacts on disease severity and mortality of older patients with COVID-19 infections were similar across studies (Niu, et al., 2020; Covino, et al., 2021; Karlsson, et al., 2021). In hospital settings, frailty (defined by the Clinical Frailty Scale or frailty index) has been validated to predict adverse clinical outcomes in different perspectives, ie, interval and rapid disease progression during hospital admissions (Lim, et al., 2021). Like the impacts of frailty on most clinical conditions, the diagnosis, treatment, and outcomes of COVID-19 was also strongly influenced by frailty, disability, and dementia that needs special attentions. With the success of vaccine development, the strategies to respond to COVID-19 pandemic gradually shifted from border controls, quarantine, and lockdowns to vaccinations and specific therapeutic agents.

However, COVID-19 vaccination on frail older adults is challenging because they may be benefited and harmed by the newly developed vaccines. Overall, 24.8% of participants in the Moderna vaccine trial were people aged 65 years and older (Baden, et al., 2021), and the Oxford-AstraZeneca trial enrolled 5% participants aged over 70 years (Voysey, et al., 2021). Although these COVID-19 vaccine trials enrolled certain proportion of older adults, these trials only enrolled older adults with stable conditions. In the real world practice, the Norwegian government provided BNT162b2 mRNA vaccines for approximately 35,000 nursing home residents (mean age over 87 years), and received 100 reports of suspected fatal adverse events (Wyller, et al., 2021). After examinations of the expert groups, 10 probable and 26 possible vaccine-related fatal events were concluded, which approximately equaled to 1 potential vaccine-related fatality in 1,000 residents. Compared to healthy older adults receiving COVID-19 vaccines, nursing home residents showed higher vaccine-related fatality rate. The potential vaccine-related fatal events may be the existing frailty and disability, but not older age per se. Nevertheless, the post-vaccination deaths have attracted public attentions and concerns to COVID-19 vaccines of all brands …