Introduction
The COVID-19 pandemic has brought numerous negative consequences for older adults. The disease has caused additional complications, morbidity, and mortality, particularly in those older adults with underlying diseases [1]. Besides the medical impacts of pathogens, COVID-19 has devastating psychological and social impacts on the general health of older adults [2]. During the pandemic, older adults exhibit higher levels of anxiety, depression, interpersonal conflicts, and social isolation but lower levels of well-being [3, 4, 5, 6]. Evidence suggests that more than 75% of deaths caused by COVID-19 occurred in the age group of 65 years old and over [7]. In addition, higher mortality rates have been reported in frail people [8].Therefore, it has been recommended to take preventive interventions and more targeted approaches to prioritize older adults with comorbidities [9]. 
Frailty is one of the predisposing factors in older adults, which can increase the prevalence of diseases and incidents among them. As per Xue’s (2011) definition, frailty is “a clinically recognizable state of increased vulnerability resulting from aging-associated decline in reserve and functions across multiple physiologic systems such that the ability to cope with everyday or acute stressors is comprised” [10]. The prevalence of infectious diseases is also remarkably high among frail people [11]. Their access to health services might be difficult due to physical or mental limitations [12]. Hence, it is important to pay special attention to the health of this group during a pandemic crisis such as COVID-19.
Despite the debates, vaccination has been accepted as one of the world’s most preventive measures against COVID-19 [13]. According to a World Health Organization (WHO) report, 13156047747 vaccine doses were administered worldwide until January 25, 2023 [14]. Older adults have been prioritized for receiving the COVID-19 vaccine in many countries, and the vaccination acceptance rate has increased among them [15]. However, two important issues should be considered when vaccinating older adults with frailty. First, many elders are homebound and cannot depart to the health centers for vaccination. Furthermore, there are not enough in-home vaccination services for them in many parts of the world, and many are not even identified [16, 17]. Second, there is no consensus on the vaccine’s effectiveness among this group of older adults [18]. Hussein et al. believed that a weaker immune system in frail older adults causes a poor response to COVID-19 vaccination [19], and Norway reported 23 deaths in frail older adults after vaccination [20]. However, WHO recognized that the vaccine did not result in an unexpected increase in fatalities or any unusual adverse events in most frail older adults [21].
Both frailty and COVID-19 can vastly influence older adults’ biological, psychological, and social aspects [22-24]. Although many studies have considered diagnoses and treatment issues in this group of older adults (e.g. higher mortality rates in COVID-19), the available psychosocial data are mostly outspread, different, or contradictory. Therefore, a comprehensive review is required to collect, integrate, and compare these results to classify our current knowledge. This study aims to review and classify published studies on the psychosocial impact of COVID-19 in frail older adults and identify the knowledge gap with a holistic approach.

Materials and Methods
In the current study, an integrative review method has been applied to explore, summarize, and integrate literature to provide a more comprehensive understanding of the psychosocial aspects of frail older adult’s life during the COVID-19 pandemic. This method allows researchers to collect, classify, evaluate, and analyze quantitative and qualitative papers, detect the knowledge gaps in the literature, link different subject areas, and present new questions or concepts [25]. The study passes five stages.
1) Problem identification, 2) Literature search, 3) Data evaluation, 4) Data analysis, 5) Interpretation and presentation of results (discussion and conclusion) [26].

Literature search and data collection
Data collection was conducted between May and August 2022. The inclusion criteria comprised all qualitative and quantitative published papers in the PubMed, Web of Science, and Scopus databases with the search strategy shown in Table 1.



Data evaluation
Following the study objectives, we used the subsequent criteria to evaluate papers and extract the irrelevant papers: A) Studies without having a specific sample group of frail older adults (60 years and over) or without presenting a particular result for them, B) studies on institutionalized individuals and inpatients, C) studies on medical issues such as diagnosis, assessments, treatments, outcomes, prognosis, and mortality rates, D) Case reports, editorials, commentaries, and other papers without specifying a certain method, and E) Papers without available full text, such as poster presentations.
As shown in Figure 1, we initially found 3577 articles, which were reduced to 2066 after removing the duplicates. When the irrelevant titles were removed, this number dropped to 353. We examined the abstracts and omitted those papers that did not meet inclusion criteria or those with corresponding exclusion criteria. Subsequently, 112 papers with full text remained. After review, 50 articles were selected (published between November 2020 and August 2022) for the final analysis (Figure 1).
Distribution and connections between the keywords of the final papers were illustrated by a VOSviewer software, version 1.6.16.

3. Results
In this study, we categorized the main findings from 50 studies to make them comparable and understandable. Figure 2 displays the distribution and connections between the keywords of the selected papers for final analysis. As shown in Table 2, most studies were qualitative and were conducted in developed countries.






The highest number of studies belonged to Japan (n=13, 26%), Italy (n=5, 10%), Canada, Spain, the UK, the US, and Spain (n=4 each, 8%), and China (n=3, 6%). The main findings of the reviewed papers have been clustered into three categories: Social consequences, psychological impacts, and preventive measures (Table 3).






Social consequences
Much evidence in the current review indicates that the raised prevalence of frailty and the incidence of transition to a frailty state during the COVID-19 pandemic can be due to the implementation of constraints during the crisis [41, 42, 50, 54, 60, 62, 72, 74]. It has been reported that frail seniors’ social activities and interaction with friends and family declined during the pandemic [52]. On the other hand, a lack of social activities was associated with a higher risk of frailty [40, 58]. Older people living alone demonstrated more decline in their physical activities and frailty [30, 36]. Higher levels of frailty and disability have also been reported after COVID-19 hospital discharge [66], and frail survivors require more care [29, 32]. Moreover, the results of some studies indicated that access to medical and social services declined during the pandemic [34, 49, 51, 68], worsening frailty status [35, 37, 43]. These conditions influenced frail seniors’ well-being and quality of life [53, 60].

Psychological impacts
The analysis of the extracted papers indicated that the general mental health of frail older adults deteriorated during the COVID-19 pandemic [39, 46, 48, 49, 67]. Depressive mode and anxiety are two major psychological effects of the pandemic on frail seniors [33, 48, 54, 55, 62, 63]. Depressive mood was associated with lower physical activity and a correlation between cognition and physical decline in frail older adults with hypertension during the pandemic [30, 64]. On the other hand, cognitive deterioration was also reported during the pandemic [48, 70]. Frail older adults reported fewer coping behaviors for health maintenance compared with their robust counterparts, and the restrictiveness of lockdown negatively affected their well-being [51, 53, 60].

Preventive measures
In response to the COVID-19 negative psychosocial impacts on older seniors, the researchers recommended some preventive measures, including simple activities such as reading. One of the dominant non-medical intervention programs to prevent worsening frailty during the pandemic is programmed exercises [38, 45, 47, 53, 65, 76]. Social support is also reported as an important preventive measure as well. Telecommunication facilities were reported as effective tools to identify and meet the needs of frail seniors during the pandemic [31, 44, 50, 59], although some clients were more comfortable with the telephone than using the new technologies [50]. Performing reading activities and boosting social networks were associated with higher physical activity levels [30]. Perceived age-friendliness of the environment mitigated the impact of lockdown on well-being and frailty [53]. There is no consensus on the efficacy of vaccination in frail seniors. Still, as COVID-19 can instigate worse outcomes in frail people, such as more disability and longer care needs, vaccination has been recommended for these vulnerable people [56, 57, 69].

Discussion
The results of the current integrative review indicated that the COVID-19 pandemic has complex, serious adverse effects on the psychosocial aspects of the lives of frail seniors. The lockdown, restrictions, and limited access to health services caused a decline in social activities, social relations (resulting in weaker social capital), physical activities, and psychological health, resulting in an increase in the prevalence and incidence of frailty in the pandemic era. These conditions lowered their mental health, quality of life, and perceived well-being. In return, frailty aggravation in the pandemic can also negatively impact psychological health and physical activities. This vicious cycle is shown in Figure 3. Initially, COVID-19 restrictions were implemented to protect people, but such social and physical limitations could negatively affect older adults’ physical activity and mental health [77, 78]. These conditions negatively affect frail older adults and need re-organization of healthcare systems for more sufficient interventions. Additionally, long-term psychological consequences should be considered for this vulnerable group [79]. Anxiety and depression are two psychological consequences of the pandemic restrictions in older adults [80]. Perceived loneliness may also be associated with significant psychological distress due to the lockdown condition [81]. In other words, these effects were more severe among older adults living alone and interacting less with their neighbors [82].
Although social distancing and stay-at-home orders are crucial for frail older adults during pandemics, maintaining social connections with others can reduce social isolation and exclusion [83]. The health benefits of socialization and interaction with others have been highlighted for older adults. As social distancing can reduce these interactions and cognitive stimulation, the solution lies in using technologies such as social media and telephone or video calls for older frail adults, along with appropriate guidance [84]. 
As frailty manifests itself by physiological declines in different systems, interventions and broad-based approaches are needed to empower frail people and their caregivers during the pandemic [84]. The impacts of limited access to social and health services during the lockdown may accelerate frailty in older adults [79, 80]. Therefore, special attention should be paid to preventive measures. Some of the suggested preventative measures are simple, feasible, and do not require special equipment. For instance, exercises such as strength, balance, and walking are useful for frail older adults during the pandemic to prevent the worsening of frailty [77]. In this regard, telehealth can assist more senior people in following their exercise delivery during the pandemic, and it is potentially more effective in addressing the needs of older adults in remote areas [80]. Interventions through education and telephone follow-up can also reduce the burden of care of caregivers of older adults [85]. Nursing students were reported to have sufficient confidence in using telemedicine for frail people during the pandemic, and they confirmed its validity and importance [86].
Although public vaccination is recognized as an important preventive measure to control contagious diseases, there is still some public mistrust about the effectiveness of COVID-19 vaccination [15, 18]. Frail adults have been reported to have a weaker immune system, which is a predisposing factor for a higher risk of adverse outcomes and mortality due to COVID-19. This decline can also lead to a poor immune response to vaccination [19]. On the other hand, the results of a study by Seiffert et al. do not confirm the above assumption. They reported that increased anti-SARS-CoV-2 IgG antibody levels after mRNA COVID-19 vaccination (with BNT162b2) in long-term facilities did not correlate with frailty and age [87]. It can be assumed that there is a knowledge gap in basic research and clinical practice [88]. Filling these gaps is critical for maintaining confidence in vaccinating frail older adults against COVID-19. In this regard, surveillance and evaluation of COVID-19 vaccination are important. Accordingly, continuous consultation with geriatricians in regulatory and advisory decision-making is necessary [89].

Conclusion
As pandemics such as the COVID-19 outbreak impose great psychosocial strains on frail older adults, more supportive and preventive measures should be taken for them. The results of this review can assist policymakers in considering appropriate social support for frail seniors during pandemics. Prescribing physical and reading activities and boosting social networks can prevent worsening frailty during pandemic-related restrictions. Since most studies are quantitative and have been conducted in developed countries, further qualitative inquiries are suggested to explore the challenges of frail older people during the pandemics in developing countries.
As a limitation of the current review, it should be noted that some studies may have included subgroups of frail older participants in their sample groups without mentioning the word “frail” in their Titles or Abstracts. Even if they presented results and reports on the psychosocial problems of frail seniors, they have not been included in our literature review.

Ethical Considerations
Compliance with ethical guidelines
This review study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (Code.: IR.USWR.REC.1400.097).

Funding
This project was funded by the Deputy of Research and Technology, University of Social Welfare and Rehabilitation Sciences.

Authors' contributions
Choosing the search strategy: Mohammad Saatchi and Arya Hamedanchi; Selection of the papers: Arya Hamedanchi and Nasibeh Zanjari; Resolution of disagreements: Yadollah Abolfathi Momtaz; Rechecking of the papers: Tahereh Ramezani; Final analysis: All authors with the supervision of Ahmad Delbari and Hamid Reza Khankeh. 

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
The authors would like to thank the Deputy of Research and Technology of University of Social Welfare and Rehabilitation Sciences for their cooperation in the project.


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