Social Distancing and Isolation Strategies to Prevent and Control the Transmission of COVID-19 and Other Infectious Diseases in Care Homes for Older People: An International Review

Older people living in care homes are at high risk of poor health outcomes and mortality if they contract COVID-19 or other infectious diseases. Measures used to protect residents include social distancing and isolation, although implementation is challenging. This review aimed to assess the social distancing and isolation strategies used by care homes to prevent and control the transmission of COVID-19 and other infectious diseases. Seven electronic databases were searched: Medline, CINAHL, Embase, PsycINFO, HMIC, Social Care Online, and Web of Science Core Collection. Grey literature was searched using MedRxiv, PDQ-Evidence, NICE Evidence Search, LTCCovid19.org and TRIP. Extracted data were synthesised using narrative synthesis and tabulation. 103 papers were included (10 empirical studies, seven literature reviews, and 86 policy documents). Strategies used to prevent and control the transmission of COVID-19 and other infectious diseases included social distancing and isolation of residents and staff, zoning and cohorting of residents, restriction of resident movement/activities, restriction of visitors and restriction of staff working patterns. This review demonstrates a lack of empirical evidence and the limited nature of policy documentation around social distancing and isolation measures in care homes. Evaluative research on these interventions is needed urgently, focusing on the well-being of all residents, particularly those with hearing, vision or cognitive impairments.


Introduction
The care home (CH) sector provides care for diverse population groups; the focus of our work is older people, many of whom live with complex and often multiple health needs [1,2]. The CH sector is heterogeneous, but we have used the term 'care home' within this work to refer to all long-term care facilities, nursing homes, residential care homes and skilled nursing facilities for older people, which differ substantially in their case mix, skill mix and staffing ratios. SARS-CoV-2, also known as COVID-19, is a rapidly emerging infectious disease [3], and healthcare setting transmission plays a vital role in its spread [4,5]. Older people living in CHs are at high risk of poor health outcomes and 1.
What mechanisms and measures have been used to implement social distancing and isolation for residents and staff? 2.
How are they implemented? What are the challenges and facilitators to implementation? 3.
What is the impact of the implemented measures and mechanisms? a.
What are the psychosocial and physical consequences for older people? b.
What are the consequences for family members, staff, and organisations? c.
What is the evidence of measures and mechanisms that work for different CHs and resident needs? d.
What recommendations have been made after the implementation of these measures?

Literature Searching and Analysis
The search strategy was developed in consultation with Information Services Specialists at (name of institution blinded for review): "nursing home* OR care home* OR long-term care* OR long term care* OR aged care facilit* OR aged-care facilit* OR residential care home* AND infect* control* OR infect* prevent* OR cohort* OR zon* OR quarantin* OR social distanc* OR prevent* OR isolat* AND acute respiratory infection* OR clostridium difficile* OR diarrhoea OR vomit* OR methicillinresistant staphylococcus aureus* or SARS* OR MERS-CoV* OR flu* OR SARS-CoV19 OR SARS-CoV-2 OR COV* OR Corona* This search strategy was run on 13 January 2021 in seven electronic databases: (Medline, CINAHL, Embase, PsycINFO, HMIC, Social Care Online, and Web of Science Core Collection) and a total of 4753 papers were identified. Grey literature relating to policy and organisational-based material was also searched between 20-24 January 2021 (MedRxiv, PDQ-Evidence, NICE Evidence Search, LTCCovid19.org and TRIP) and 13,488 articles were identified. After removing the 1465 duplicates from these 18,241 documents, 16,776 articles remained, and the titles and abstracts were screened independently by two reviewers using the inclusion and exclusion criteria. These were: the literature needed to address  or other infectious and contagious diseases in older people (aged 65 years and over) living in CHs, nursing homes, long-term facilities, or residential CHs. No limits were placed on the geographical location, but only English-language articles were included because of the resources available. 145 abstracts were identified as potentially relevant, and these papers were independently reviewed in full by four reviewers using the inclusion and exclusion criteria to make a recommendation: 'Include'; 'Exclude'; 'Unsure-need to conduct full text screening' (each paper was reviewed by two reviewers and any conflict in the assessments were resolved in collaboration with a third reviewer). 94 records were included in the review. Targeted searching of the reference lists of these 94 papers highlighted a further 10 papers, which were again reviewed independently by two reviewers, and nine were included in the review. Thus, a total of 103 papers were included in the review [6,7, (see Table 1 for a description of each paper), and 52 papers were excluded . Table 1. Overview of the 103 papers included in the rapid review.

Author Title Year Scope
Akkan and Canbazer [10] The Long-Term Care response to COVID-19 in Turkey 2020 Policy paper highlighting Turkey's response to the COVID-19 pandemic.
Anderson et al. [11] Nursing home design and COVID-19: Balancing infection control, quality of life, and resilience 2020 Special article to discuss the need for care homes to examine architectural design models.
Arling and Arling [12] COVID-19 and long-term care in the US State of Minnesota 2020 Policy paper highlighting US State of Minnesota's response to the COVID-19 pandemic.
Arlotti et al. [13] MC COVID-19 Governmental response to the COVID-19 pandemic in long-term care residences for older people: preparedness, responses and challenges for the future. Italy 2021 Policy paper highlighting Italy's response to the COVID-19 pandemic.
Ayalon [15] Long-term care settings in the times of COVID-19: Challenges and future directions 2020 Commentary on the challenges experienced in care homes during COVID-19.
Australian Government [14] CASE STUDY: Dorothy Henderson Lodge 2020a Case study example of a care home's battle against COVID-19.
Baron-Garcia et al. [16] Measures adopted against COVID-19 in Long-Term Care services in Catalonia 2020 Policy paper highlighting Catalonia's response to the COVID-19 pandemic.
Belmin et al. [17] Coronavirus Disease 2019 outcomes in French nursing homes that implemented staff confinement with residents 2020 Retrospective cohort study conducted to investigate COVID-19-related outcomes in French nursing homes that implemented voluntary staff confinement with residents.
Bergman et al. [18] Recommendations for welcoming back nursing home visitors during the COVID-19 pandemic: Results of a Delphi panel 2020 Delphi study to generate consensus guidance statements focusing on essential family caregivers and visitors.
Blain et al. [19] August 2020 Interim EuGMS guidance to prepare European Long-Term Care Facilities for COVID-19 2020 To guide long term care facilities in preventing the entrance and spread of SARS-CoV-2.
British Geriatrics Society [6] Managing the COVID-19 pandemic in care homes for older people 2020 Guidance developed to help care home staff and NHS staff who work with them to support residents through the pandemic.
Browne et al. [20] Policy response to COVID-19 in Long-Term Care Facilities in Chile 2020 Policy paper highlighting Chile's response to the COVID-19 pandemic. Rios et al. [82] Guidelines for preventing respiratory illness in older adults aged 60 years and above living in long-term care 2020a To identify infection protection and control recommendations from published clinical practice guidelines (CPGs) for adults aged 60 years and older in long-term care settings.
Rios et al. [83] Preventing the transmission of COVID-19 and other coronaviruses in older adults aged 60 years and above living in long-term care: a rapid review 2020b To examine the current guidelines for infection prevention and control of coronavirus disease-19 (COVID- 19) or other coronaviruses in adults 60 years or older living in long-term care facilities (LTCF).

Schmidt et al. [84]
The impact of COVID-19 on users and providers of long-term care services in Austria 2020 Policy paper highlighting Austria's response to the COVID-19 pandemic.
Scopetti et al. [85] Expanding frontiers of risk management: care safety in nursing home during COVID-19 pandemic 2021 Discussion paper on care safety in nursing homes during the COVID-19 pandemic.
Shallcross et al. [86] Risk factors associated with SARS-CoV-2 infection and outbreaks in Long Term Care Facilities in England: a national survey 2020 Cross-sectional survey to identify risk factors for SARS-CoV-2 infection and outbreaks in long-term care facilities (pre peer-review manuscript).
Shi et al. [87] Report from mainland China: Policies to support long term care during the COVID-19 outbreak 2020 Policy paper highlighting policies to support long term care during the COVID-19 pandemic.
Shrader et al. [88] Responding to a COVID-19 outbreak at a long-term care facility 2021 Describes an outbreak of COVID-19 in a long-term care facility (LTCF) in West Virginia that was the epicentre of the state's pandemic. Data were extracted from the 103 included papers into a bespoke extraction form, using an Excel spreadsheet, which was reviewed and tested within the team. Data items included: author(s) and year of publication; study aim; study design; setting and participants; intervention(s) discussed, including a description of the measure(s) used (e.g., what it was; who it was for; how it was implemented, factors supporting or hindering its implementation); findings; and author recommendations. Findings from the 103 papers were synthesised using tables and a narrative summary. The narrative synthesis was organised around the review questions: interventions for the prevention and control of COVID-19 and their impact; challenges and facilitators for implementing COVID-19-related interventions in care homes; and interventions for the prevention and control of other (non-COVID-19 related) infectious diseases. Figure 1 highlights a flowchart of the review process.

Findings
The 103 papers consisted of 10 research studies, eight of which explored COVID-19 and two explored other infectious diseases. Two empirical studies mentioned social distancing interventions [90,99], nine mentioned isolation interventions [17,32,54,58,81,86,90,97,99], eight mentioned restrictions [17,18,58,81,86,90,97,99] and two mentioned zoning or cohorting [90,99]. However, it should be noted that these interventions were generally mentioned as part of a wider discussion of COVID-19 strategies and were not the main focus of the studies. Three of these empirical studies were conducted in the UK, four were conducted in Europe, two in Asia and one in North America. The design of the 10 research studies was heterogenous. Seven different quality assessment tools were used by a single reviewer to conduct a risk of bias assessment, with verification of judgements by a second reviewer: from the Critical Appraisal Skills Programme (CASP) checklists for RCTS, qualitative research and cohort studies [164]; the mixed methods appraisal tool (MMAT) [165]; from the Joanna Briggs Institute (JBI) checklists for analytical cross-sectional studies and prevalence studies [166]; and Jungers (2017) guidance for reporting on Delphi studies [167]. There was reviewer agreement that all 10 studies should be included in the review.
Also included in this review were 86 policy documents/grey literature and seven literature/rapid reviews. Grey literature came from around the world and included policy documents highlighting different countries' responses to the pandemic, guidance/guidelines for CHs, briefing documents, discussions, and commentaries. The included literature/rapid reviews were of varying quality (some were pre-print and not peer-reviewed), with five related to COVID-19 and two related to other infectious diseases. All papers highlighted the various strategies used by CHs to prevent or control the transmission of COVID-19 and other infectious diseases amongst their residents and staff, including not only strategies of social distancing and isolation, but also restrictions, zoning and cohorting. However, once again, the focus of grey literature and reviews was generally on overall responses to the pandemic, with these specific interventions mentioned as one component of this. Other strategies, such as the use of personal protective equipment (PPE), testing, ventilation, and adequate hygiene procedures, were also highlighted but are outside the scope of this review.

Interventions for the Prevention and Control of COVID-19
The following interventions were discussed specifically in relation to the spread of COVID-19:

Social Distancing
The terms 'social distancing' and 'physical distancing' were used interchangeably within and across papers, but for purposes of consistency they are referred to as 'social distancing'. There was little discussion of social distancing interventions within CHs. The term was not defined in the literature or what it meant in practice, other than that, CHs must adhere to 'government guidance' or 'national rules' on distancing. Those who did describe their understanding of distancing stated this was maintaining a distance from other people of at least one to two metres in Europe or six feet in the US [19,24,46,57,75,104,107].

Social Distancing for Residents
Social distancing generally referred to those residents who had not been exposed to COVID-19 being able to continue with some regular routines and group activities whilst maintaining a distance from others [24,34,37,40,47,51,57,62,68,75,82,83,90,99,104,107,110]. This included socially distanced mealtimes in the dining room [47,51,62,99,107]; separated chairs in common rooms [51]; one-way movement systems around the home [41]; and spacing indicators on the floors [51]. Some papers stated that social distancing measures enabled residents to maintain a "normal" life during the pandemic [24]. However, other homes decided not to enforce social distancing measures, knowing that their residents would not be able to adhere to them [62]. Very little was stated about the impact of social distancing measures on residents other than acknowledging that they may have severe implications for their mental health and wellbeing [107]. Residents with cognitive impairment or dementia were also reported to have greater difficulty understanding and abiding by social distancing measures [6,94].

Social Distancing for Staff
Some papers discussed the importance of social distancing among staff, for example, in staff rooms and other areas around the CH [16,46,51,73,75,107,110], including separating chairs in staff rooms [51], staggering breaks to limit the density of staff in specific areas [57], and restricting staff car sharing to/from work [57]. No reports of the impact of social distancing on staff were identified.

Isolation
The terms 'quarantine' and 'isolation' were used interchangeably within and across papers, but for consistency are referred to as 'isolation':
Two policy papers stated that where isolation was not undertaken effectively, the virus spread amongst CH staff and residents [13,47]. One (pre-peer review) empirical study [86] also reported higher odds of outbreaks in CHs with poor compliance with isolation procedures. However, there was evidence from empirical research, literature reviews and policy documents that the isolation of residents could have negative effects upon their physical and mental health [6,12,24,34,48,62,90,94,97,103,106]. This was particularly notable for those with dementia, cognitive problems, autism, and learning difficulties, who might not fully comprehend instructions [15,34,38,62,68,90,94,107]. For these individuals, agitation and behavioural disturbances were reported [15,48,107], and one commentary paper stated this may have required the increased use of restraint [15]. Isolation has also been associated in the grey literature with decreased movement and mobility [24,47,106,107]; increased postural disorders [24]; increased risk of falls [24]; and increased sarcopenia and deep vein thrombosis [19]. Isolated CH residents have been reported in empirical research and policy documents to have poorer fluid/food intake, leading to weight loss, malnutrition and difficulties maintaining hydration [24,26,48,81,88].

Isolation of Staff
Isolation measures were implemented for CH staff, such as an isolation period for those returning from a hospital stay [87,99] or international travel [72,102]. Isolation was also required for those staff who had COVID-19 symptoms or who had contact with someone with COVID-19 [14,19,33,[36][37][38]51,52,57,62,68,75,107,110]. Usually, the isolation period for staff was 14 days [16,33,52,56,68,75], but in some cases staff could return to work after ten [57] or seven days [16,68]. Grey literature stated that isolation guidelines for staff could adversely affect CHs by creating significant staff shortages [21,33,67], and there were reports of some homes experiencing dilemmas around this. For example, there were accounts in the US of staff who had come into contact with COVID-19 being asked to continue working if they did not display symptoms themselves [75] and in the Netherlands, some CH staff were asked to keep working while sick [21,67]. There were also examples from New Zealand of residents being transferred to hospitals due to insufficient staff available to care for them [72].
Empirical research papers, literature reviews and policy papers referred to 'zoning' residents with a positive COVID-19 test result/suspected COVID-19 away from those without [6,12,19,27,29,33,35,36,42,46,52,68,81,84,88,90,109,110]. The intervention of zoning was reported to offer CHs a clear delineation of risk zones throughout the building and it was stated that staff, residents, and equipment should not move between the zones to reduce cross-contamination [12,19,29,33,41,46,52,110]. Separate staff entrances, exits and corridors for each zone were used, where possible [19,41,46,52,90,99], with staff communicating via telephone [41,52]. This intervention allowed CH zones to operate as self-sufficient care bubbles [52], enabling residents to have limited freedoms within their zone [6,27,42,81], encouraging socialisation and activity within the zones and helping decrease residents' feelings of isolation and loneliness [90]. Cohorting was sometimes suggested in the grey literature for settings where it was impossible to physically separate residents [19]. Examples of cohorting were organising residents into small groups/dedicated areas within a floor (rather than separate floors or wings) with the same staff continuously assigned to them [19,41,51,58,63,75,96,106,107,109]. The rationale for this was that, in case of infection within this small group, as few residents and staff as possible would require isolation [58].
There was some empirical research evidence that staff working solely within an allocated zone/cohort of residents helped prevent the spread of COVID-19 [86]. However, such interventions depend upon CHs having sufficient staff resources [90] and can result in financial costs [41]. Indeed, examples in the grey literature were provided where zoning and cohorting interventions required CHs to recruit new team members or to use 'surge staffing' (i.e., pre-identified temporary, casual labour) [36,41]. There was some evidence from empirical research and the grey literature that moving residents from their standard room to a new cohort/zone could create confusion, anxiety, or distress for residents [40,90]. Still, it was acknowledged that, for many, the benefits were likely to outweigh the negative consequences [90].

Restrictions
Although this review focussed upon social distancing and isolation interventions, other related interventions of 'restrictions' were also regularly discussed. For this review, the term 'restrictions' referred to any instances where an individual was prevented from doing something they would normally do (e.g., cancelling activities) or asked to modify how they would typically do something (e.g., asking residents to eat meals in their bedroom). We have separated this from 'social distancing' (which referred to instances where an individual could carry on activities of everyday life whilst remaining at a distance from other individuals) for the purpose of clarity, but these terms were used interchangeably within the literature.

Restrictions Placed upon Staff
Several papers also talked about the restrictions placed upon staff members [17,86]. These restrictions involved changes to working patterns, such as shift length, rota patterns, and extended working hours [10,24,42,51,57,70]; limiting the number of settings staff could work within [33,40,42,52,61,83,110]; and asking staff to live within the CH for extended periods [17,40,53,77,109,110]. Policy papers stated that professional practices were redefined, with tasks modified and adapted to suit new working rhythms and procedures, such as sorting bedding, disinfecting premises and serving meals [24]. In the US, staff training and certification requirements were modified to reinforce the available workforce [31,55], whilst Australia, New Zealand and Malaysia increased the maximum weekly working hours allowed by international students and those with restricted work visas [33,56,72]. Slovenia restricted CH staff's right to leave their employment or strike [33]. There was some empirical evidence that staff confinement in CHs could be beneficial for transmission rates, though only one research study explored this [17], alongside anecdotal evidence in a news article [53]. There was, however, suggestion from literature reviews and policy documents that new ways of working and more significant staff absences increased workloads and led to stress, exhaustion and burnout [24,27,34,35,48,62,69,103].
There was evidence from the empirical research, literature reviews and policy documents that visitor restrictions negatively impacted residents' health and wellbeing, with residents reported to be confused, distressed, and frustrated by not seeing their family [10,35,48,58,62,88,91,94,97,100,103,106,108]. In one research study, residents did not recognise their families after restrictions had eased [97]. These restrictions also negatively impacted the well-being of families, with reports of guilt, fear, worry and isolation [26,34,47,60,69,73,90,96,103,107]. Some residents died without having their family with them [58,60,63,91,96], which was distressing for families [34,60,90,96] and staff [60,90]. One policy paper stated that some CHs experienced financial difficulties when older people expressed reluctance to move into them due to fears they would be isolated from their families [21].

Restrictions Placed upon Other Professionals and Services
In many instances, all but essential professionals/services were restricted from entering CHs during the COVID-19 pandemic. This included healthcare professionals (e.g., physicians, psychologists, physiotherapists etc.) and non-healthcare workers, (e.g., hairdressers, entertainers, and volunteers) [17,18,36,40,72,75,96,97,102,110]. Generally, healthcare services moved towards virtual or remote ways of working, including video calls/ consultations and virtual ward rounds/multidisciplinary team meetings [40,62,70,90,99,102]. There were some concerns in the grey literature that restricting professionals from entering CHs may have prevented residents from receiving necessary medical and social care [45,95,107]. Concerns have also been raised in the grey literature about the quality of care provided to residents during periods of restrictions, as external regulators did not enter CHs to undertake inspections for quality assessments or advisory visits [30,33,48,55,70,95]. Table 2 highlights the challenges and facilitators reported impacting the success of implementing COVID-19 interventions in CHs. Table 2. Challenges and facilitators of implementing COVID-19 interventions in care homes.

Sufficient staff support
Having sufficiently supported staff helped facilitate the successful implementation of COVID-19 interventions. This included ensuring staff were paid for any time spent in isolation [34,48,81,107]; rewarding staff with annual pay increases or bonuses, gifts, care packages or additional leave days [34,52,61,81]; providing food and water stations to ensure staff were adequately fed and hydrated or providing access to wellbeing initiatives, counselling, and emotional support [42,52,81].

Lack of guidance/clarity from governments
Implementing COVID-19 interventions was made more difficult by the lack of guidance and clarity from governments around when and how interventions should be applied, with policy measures often scarce, flawed or adopted late [21,24,30,34,55,60,62,81,95,108].

Good communication
Having good communication and the availability of informational materials, such as brochures, posters and signage on COVID-19 and the associated policies helped explain the reasons behind COVID-19 interventions to residents and their families and friends [14,28,36,40,75,104].

Physical space and layout of care homes
The physical space and layout of some care homes made implementing COVID-19 interventions more difficult. For example, not all care homes had the space to provide single rooms, to create separate 'zones' or to ensure sufficient walking space around the home in line with social distancing measures [11,38,42,56,60,62,81,90,103,109].

Use of innovative technology
Innovative technology and software such as Zoom, Facetime or Teams helped remotely support residents and their families during periods of restriction and reduce the impact of social isolation [33,42,44,60,90,99]. However, some problems were highlighted around having insufficient equipment, broadband or Wi-Fi within care homes [30]; as well as the requirement for staff, families and residents to have training on how to use the technology [107].

Social Distancing
Only two papers from the grey literature discussed social distancing measures for non-COVID-19 related infectious diseases [80,98]: one stated there should be at least two metres between residents with and without signs and symptoms of influenza [80] whilst the other said that CHs should maintain a one-metre distance between all residents during outbreaks of respiratory infection [98].

Isolation
Several papers discussed how isolation had been used to control the spread of other infectious diseases within CHs, such as MRSA, influenza, and C-diff [22,23,32,43,49,50,59,64,71,76,[78][79][80]89,98]. This tended to involve isolating infectious residents within their bedrooms or cohorting them where this was not possible [22,23,49,50,64,71,74,76,[78][79][80]89,98]. Some papers talked of the need to restrict admissions of new residents into the CH and/or prevent the readmission of those who had been in hospital during severe outbreaks [23,74]. Others highlighted a more flexible approach to isolation measures than there was for COVID-19. For example, one research study noted that known MRSA carriers were only asked to be separated from vulnerable residents with skin lesions or indwelling catheters, but were otherwise allowed to continue with usual social activities [32]. The importance of making decisions around isolation on a case-by-case basis was emphasised in the grey literature, as was the importance of not over-isolating residents [22,43,79,89]. There were also examples highlighted in the grey literature of staff being asked to isolate to control the spread of influenza by self-monitoring for symptoms of illness and staying away from work if feeling unwell [23]

Restrictions
Only one literature review mentioned the use of restrictions for preventing infectious diseases from entering CHs [66] and stated there was no evidence to support banning/restricting visits to CHs for this purpose. More papers explored how restrictions could control the spread of infectious disease when there was already an outbreak or suspected case within the CH. Some policy documents reported that restricting the movement of residents and visitors during an outbreak of infectious disease could be beneficial [23,50,71,74,80,89,92,98]. This included the restriction of group activities in addition to minimising the movement of visitors within the CH [23,74,80,89,98]. A Canadian toolkit reported that complete closure of CHs to visitors should not be permitted unless under the order of the Medical Officer of Health, due to the potential harm this could cause residents and families [74]. There was also less of a 'blanket approach' to restrictions reported in policy documents for other infectious diseases than for COVID-19. These included, for example, residents only being restricted from group activities when wound drainage or diarrhoea could not be contained [71] or activities only being restricted for residents in outbreak 'zone' areas [74]. Again, it was reported that clear signage and communication were important for residents and family members during any periods of restriction [98]. Some policy documents also discussed the restrictions that should be placed upon staff working patterns to control the spread of infectious diseases in CHs [23,74,89]. For example, during influenza outbreaks, a policy paper [23] reported that the movement of staff across CHs and healthcare facilities should be minimised. Similarly, where zoning/cohorting restrictions were in place, staff working within affected units should not also work within non-affected areas of the home [23,74,98]. Finally, it was suggested in the grey literature that only staff who had been vaccinated against influenza should care for those residents with suspected/confirmed influenza [23,74].
Similar challenges and facilitators impacting the success of implementing interventions for other infectious diseases in CHs were identified as for COVID-19 interventions, including the need for staff education and training around infection control measures [74,101], the design and layout of CH buildings [50,64] and good communication with residents and visitors [64].

Discussion and Conclusions
This review demonstrates the overall lack of empirical evidence and the limited nature of documentation around social distancing and isolation measures in CHs. Most papers identified within this review were grey literature or policy documents, many of which were descriptive or opinion based. Furthermore, these interventions were generally mentioned as part of a wider discussion of COVID-19 strategies and were not the main focus of the papers. Even fewer papers discussed these measures for non-COVID-19 related infections, which meant learning from this evidence base was also limited.
This review identified limited exploration of social distancing interventions to prevent and control the spread of COVID-19 in CHs. Up to the date of this review, only 10 empirical studies met the inclusion criteria, and only two discussed the impact of social distancing in CHs. This review addresses this gap and contributes to a body of research evidence that is now developing apace. Of significance is the plethora of policy documents on the topic. The grey literature provided little evidence of the effects of social distancing on resident outcomes or COVID-19 infection rates and no discussion of the impact of social distancing on CH staff. More literature explored isolation interventions in CHs, including nine empirical studies, and a key finding was the considerable variation in available guidelines and the implementation of measures, nationally and internationally. This reflects the challenges for CHs of dealing with rapidly changing multiple sets of guidance [168,169], the CH sector being ill-prepared to cope with a pandemic [168,170] and the sector not being supported well at the outset, with reports of abandonment by governments [168,[171][172][173]. These findings contribute to important lessons for decision makers about the need for comprehensible, concise, and meaningful guidance about social distancing and isolation and related measures that can be translated easily into operational policies for care homes. CHs need evidence-informed guidance that sets out what and how social distancing and isolation measures should be operationalised, whilst meeting residents' individual needs, including their fundamental rights to liberty and security, and with attention to education for residents, families, friends and staff [170]. Further, there is a need for large, evaluative, empirical studies about the impact of social distancing and isolation measures on the populations of older people living in CHs worldwide.
The most discussed intervention for preventing and controlling the transmission of COVID-19 and other infectious diseases in CHs was restrictions, which included restricted visiting from families or friends and external agencies, restricted group events and activities for residents, and restricted work arrangements for staff. There was limited empirical evidence on whether visitor restrictions prevented the transmission of COVID-19 and other infectious diseases in CHs. Thus, many authors have highlighted the importance of reintroducing visitors into CHs as soon as it is safe to do so [40,58,107], with calls for CHs to take a more flexible, risk-assessment-based approach to visits [38,67]. The urgency of this is accentuated by evidence emerging about the negative impacts of visiting restrictions on the physical, psychological, emotional and cognitive well-being of residents and their families and friends [174,175]. These findings resonate with other studies for nursing home residents [168], where restrictions resulted in several losses related to freedom, social contact, activities, communication and autonomy, and with residents describing feelings of depression, hopelessness, uselessness, and sadness. The implementation of any infection control and prevention measures must prioritise the well-being of all residents, with targeted consideration around how best to achieve this for residents living with particular care needs, such as hearing, vision or cognitive impairments.
Many CH residents live with dementia; in UK CHs, the prevalence of dementia is 69% and increasing [176]. Restrictions on the movement of residents living with dementia have been shown to have negative consequences for mental wellbeing, with an escalation of neuropsychiatric and behavioural disturbances [177]. A recent rapid systematic review of the effect of COVID-19 isolation measures on the cognitive and mental health of people living with dementia included only two studies that had been conducted in CHs [178]. Findings reported worsening of memory and mood, and reduced independence in activities of daily living. There was also an increase in mean depression and anxiety scores. Further research is required to understand more fully the experience of infection prevention and control measures, including social distancing and isolation for older people living with cognitive impairment, their families, friends and staff, to inform evidence-based practice that maximises quality of life and well-being.
Several factors were identified as supporting CHs in their implementation of interventions to control the transmission of COVID-19 and other infectious diseases, including access to innovative technology [60,90,99]; good communication with residents and families [40,64,75,104]; and ensuring CH staff were sufficiently trained and supported [42,52,61,74,101]. These findings concur with a recent review [179] to analyse the impact of COVID-19-related social distancing requirements on older adults living in long-term care facilities. Strategies proposed to mitigate the negative effects of social distancing were: the use of technology; maintaining virtual intergenerational connections; maintaining therapeutic and personalised care; and adhering to COVID-19 safety guidelines and preventive measures [179]. A coherent, agreed strategy is pivotal to support the implementation of these action points nationally and internationally. A lack of guidance and clarity from governments around when and how interventions should be applied was also identified as a potential barrier, with policy measures often scarce, flawed, or adopted late [81,95,108]. Again, nursing home staff in a recent study [168] shared that early in the pandemic, information and instructions about what to do and when were unclear, sometimes incoherent and ever-changing. CH staff have responded innovatively to the challenges of implementing social distancing and isolation measures in adverse circumstances, coping with additional workloads and resource constraints [172]. There is a need for key stakeholders, including researchers, funders, the CH sector, and governments to understand fully their experiences of actions that worked, did not work, or worked less well, and why, and to work collaboratively with CHs to ensure that their staff are supported and enabled to care well for residents and their families and friends for the duration of this pandemic and beyond.
A further barrier to social distancing and isolation interventions identified by this review was the design of CH buildings. Many CHs have insufficient space to provide single isolation rooms, create separate 'zones' or ensure sufficient walking space around the home in line with social distancing measures [90,103,109]. This is a significant issue that warrants careful discussion and planning. There have been calls for new minimum standards for the design of UK CHs so that they can respond effectively to any future outbreaks of infectious diseases whilst promoting quality of life and well-being for residents, their families, friends, and staff (https://www.buildingbetterhealthcare.com/news/article_page/Call_for_new_ minimum_standards_for_UK_care_home_design/167833) (Access on: 24 November 2021). 'Resilient building design' for CHs that addresses design for infection control as well as for improved quality of life has been recommended [11]. It is acknowledged that this is complex and multifaceted, and will evolve as new CH facilities are purposefully designed and built.
Notably, this review has contributed to clarifying terminology related to the concepts of social distancing and isolation as infection prevention and control measures within the context of COVID-19 and other infectious diseases. A key finding was inconsistency in the meaning and use of key terms such as 'social distancing,' 'isolation' and 'restrictions,' and such inconsistency across guidance, protocols and policies needs to be addressed.

Strengths and Limitations
This is an important topic and our review makes an important contribution to understanding in the field. To our knowledge, this is the most extensive review of the evidence around social distancing and isolation measures to prevent and control the transmission of COVID-19 and other infectious diseases in CHs caring for older people. Cochrane rapid review methodology was used, contributing to the quality of conduct and reporting and the robustness of the results. Our systematic and comprehensive searches of several databases and the grey literature to answer the review questions culminated in the inclusion of 103 records. The 103 papers were from around the world. Only sources published in English were included, which is acknowledged as a potential source of publication bias. Other key strategies in the prevention and control of COVID-19 and other infectious diseases, such as the use of PPE, testing, ventilation and adequate hygiene procedures, were excluded as they were outside the scope of this review, and we acknowledge this is a limitation.

Conclusions
The COVID-19 pandemic has had a devasting impact on the CH sector, and in many countries, CHs have been at the epicentre of deaths from the disease [18,81,86,99]. To help prevent and manage COVID-19, our review has advanced understanding of social distancing and isolation for older people living in CHs. The empirical phase of our study will contribute to understanding further the real-life experiences, challenges, facilitators and consequences of implementing social distancing and isolation within the CH setting, informing best practice guidance and resources.