Research evidence on cohorting patients in community hospitals during the COVID-19 pandemic was identified in Canada, the United States (US), the United Kingdom (UK), Singapore, and other international jurisdictions. In addition, nine guidance documents from the following jurisdictions provide best practices for cohorting patients: Canada, Canadian provinces (Ontario, Alberta, British Columbia, Manitoba, Saskatchewan), the UK and Australia. Themes include the rationales for cohorting in hospital settings, and the principles and recommendations for doing so, including the types of settings, and the flow of patients within a single hospital site. Some evidence about the effectiveness of hospital cohorting was also identified. A summary of these findings can be found in the section below.

Scientific Evidence

• The identified scientific evidence on cohorting in hospital settings consists of three articles (Toronto, US, Singapore), one international survey, one review, and two UK-based evaluations. Information includes the following themes:
  • Rationales for Cohorting in Hospitals: Several articles suggest that the rationale for cohorting in hospitals during the COVID-19 pandemic is to mitigate the spread of infection, limit the number of exposed health care workers, and conserve supplies (i.e., personal protective equipment [PPE]).
  • Recommendations for Cohorting in Hospitals: The following recommendations were identified in the scientific literature:
    • Single Isolation Rooms: An international review by a group of health care professionals from, or with experience in, low- and middle-income countries (LMICs) recommends that in cases where there are no single isolation rooms, or there is a surge of cases, patients with confirmed COVID-19 should be cohorted together (strong recommendation, low quality of evidence). It is also recommended that patients with suspected COVID-19 be cohorted separately or placed in isolation rooms (strong recommendation, low quality of evidence).
    • Testing: A team from the University Health Network (UHN) in Toronto, Ontario reported that effective patient cohorting requires readily available and reliable SARS-CoV-2 testing, with rapid return of results.
  • Hospital Settings: The identified literature describes cohorting patients across various health care settings, including COVID-19 units/risk-based zoning in wards, segregated isolation wards for COVID-19 cases and general multi-bed cohorted wards, and designated critical care units. For example:
    • Separate Areas for Confirmed and Suspected Cases: One UK article described the implementation of a triage tool, which involved the creation of confirmed and suspected COVID-19 wards. These ward areas were physically separated from one another by constructing doors, with a one-way flow of staff entering and exiting the ward. PPE donning and doffing stations were positioned at these fixed points of entry and exit. Bed spacing within bays was expanded by removing beds to increase the distance between patients, and all non-essential equipment was removed.
  • Flow of Patients:
    • Vulnerable Patients: One article about cohorting in US hospitals noted that at Michigan Medicine ensuring the ongoing care of vulnerable patients, such as those in the post-transplant and immunocompromised communities, remains imperative. Safe locations and staffing plans that separate vulnerable patients from COVID-19 activities are carefully considered.
    • Triage Tool to Manage Patient Flow: As noted above, a UK article evaluated the use of a triage tool to manage patient flow in the event that there would be insufficient single-occupancy rooms to isolate all suspected cases at admission. To implement this strategy an infectious diseases clinician stationed in the emergency department (ED) applied an isolation and cohorting algorithm to determine priority for single-occupancy room allocation. The authors found that this approach combined with innovative infection prevention and control (IPAC) measures reduced bed pressures without increasing the risk of health care-associated transmission. The triage tool consists of four cohorting categories (see Table 2 for details).
  • Evidence on the Effectiveness of Cohorting Patients in Hospitals During COVID-19: There is little evidence to suggest that cohorting patients with suspected or confirmed COVID-19 reduces the risk of nosocomial transmission. The international review identified some outcomes for COVID-19 and other respiratory viruses, such as SARS:
    • One study (1990) showed a reduction in nosocomial transmission of respiratory syncytial virus using cohorting with a decrease from 5.33 to 1.23 infections per 1,000/patient days of care.
    • Experience from the 2003 SARS outbreak in Singapore suggests that cohorting on an open ward may be effective in an outbreak setting.
    • Singapore’s response to the COVID-19 pandemic included designating “respiratory surveillance wards” for patients with respiratory symptoms. When SARS-CoV-2 cases were confirmed, patients were moved to a separate isolation ward. Among staff and patients exposed to SARS-CoV-2, only one patient developed COVID-19 after exposure.
    • Another article from Singapore describes a multi-tiered infection control strategy that was implemented across a health care campus, which included improved patient segregation and distancing, and heightened IPAC measures. All symptomatic patients were tested for COVID-19 and common respiratory viral infections (RVIs). Reported outcomes include:
    • Testing and Cohorting Pathways: One-third of admissions were first tested in EDs allowing for faster turnaround of results and determination of COVID-19 status upon arrival. Due to improved segregation, less than 1% of COVID-19 cases campus-wide were picked up in multi-bedded cohorted general wards, outside of designated areas for the management of COVID-19 cases.
    • No Patient-HCW Transmission: The multi-tiered infection control strategy was successful in mitigating health care-associated transmission of COVID-19 as well as common RVIs across a large health care campus, over a six-month period (January to June 2020). No documented patient-HCW transmission of COVID-19 occurred, despite caring for more than 1,500 cases of COVID-19 campus-wide.
    • The international review also notes several reports on the SARS and MERS outbreaks where entire hospitals or separate hospital wards were designated for the care of SARS or MERS patients. The reports also noted challenges. For example:
    • Challenges with Designated Hospitals: In Toronto, Ontario, establishing dedicated SARS hospitals proved challenging and instead many hospitals were prepared to care for SARS patients. When the second wave of SARS occurred in Toronto, four hospitals became designated SARS hospitals. In some settings, these strategies also resulted in dedicated teams of health care professionals, including physicians, nurses, and allied health care professions. However, in one report from Canada, HCWs who were employed in more than one hospital transmitted SARS among institutions, demonstrating the risk of transmission from HCWs.

International Scan

• International guidance documents with information about cohorting patients in hospitals during COVID-19 were identified in Australia, and the UK, including the following:
  • Recommendations:
    • Single Isolation Rooms: Guidelines from the World Health Organization (WHO), US Centers for Disease Control and Prevention (CDC), and European Centres for Disease Control (ECDC) recommend that COVID-19 patients be placed in single isolation rooms, when possible. When this is not feasible, the WHO recommends cohorting patients according to their status as either confirmed, probable, or suspected COVID-19; probable cases are defined as suspect cases for whom testing is inconclusive or not available. Other recommendations include:
    • Consult Experts: The decision to cohort patients in a health care facility should be made in consultation with IPAC experts, including infection control specialists.
    • Multiple Infections: Patients who have COVID-19 and another infection (e.g., diarrhoea or Methicillin-resistant Staphylococcus aureus) should be nursed in a single room.
    • Dedicated Units and Staff: The US CDC (2020) recommends that health care facilities designate entire units to COVID-19 patient care, assign dedicated health care professionals to these units, as a measure to limit health care professionals’ exposure and conserve PPE.
    • Planning and Communication: On each hospital site, wards and wards with suitable bed bays will be identified and a pathway agreed from ED to discharge. This will be communicated to the appropriate staff at huddles/briefs to support patient/bed management. Daily updates on bed spaces on cohort wards/bays should be available to support patient transfers from ED and acute receiving.
    • Setting Up the Cohort: The cohort bay should have dedicated equipment as far as possible such as blood pressure, oxygen saturation and temperature recording devices within the cohort bay. A trolley with fresh linen, tissues, waste bags and commonly used disposable equipment such as oxygen tubing and masks will be useful for staff working in the cohort. Use the IPAC yellow sign at the entrance of the cohort.
    • Bed Spacing: Patients should be separated by at least two metres from each other in a cohort area, and bed curtains can be drawn as an additional physical barrier if possible.
  • Guidance on Settings: In most jurisdictions, patients are cohorted in inpatient units, floors, or wards. For example, in Western Australia, hospitals may consider creating cohort wards, especially in those facilities where heating, ventilation air conditioning  systems can be isolated. Cohort wards should be separate from other patient areas and are not to be used as a thoroughfare.
  • Guidance on Flow of Patients: There is little available information on the movement of cohorted COVID-19 (confirmed or suspected) and/or non-COVID-19 patients across hospital sites. In the UK, patients who have confirmed COVID-19 can be nursed in a COVID-19 cohort until they are deemed no longer infectious. Patients who remain symptomatic but are well enough to be discharged can be sent home with advice on how to self-isolate.

Canadian Scan

• Guidance documents with information about cohorting patients in hospitals during COVID-19 were identified in Canada, British Columbia, Alberta, Saskatchewan, Manitoba, and Ontario.
  • Principles/Recommendations: Manitoba and Saskatchewan do not routinely advise cohorting and then only for laboratory-confirmed cases. Other principles and/or recommendations include:
    • Consult Experts: The decision to cohort patients in a health care facility should be made in consultation with IPAC experts, including infection control specialists.
    • Testing: Effective cohorting of patients requires readily available and reliable testing for SARS-CoV-2, with rapid return of results.
    • Zones of Risk: Concentric zones of risk can be established around individual patient rooms (red zone, highest risk) to the hallway (green zone, intermediate risk) and to the nursing station (blue zone, lower risk). Principles include minimizing traffic between zones and providing visual barriers to prompt use of full PPE in the red zone.
    • When cohorting patients who are lab confirmed, recommendations suggest treating each bed space like a private room. Washrooms may only be shared by confirmed positive patients.
  • Guidance on Settings: Two Canadian jurisdictions cohort patients in inpatient units, floors, or wards. Manitoba’s Health Sciences Centre’s 30-bed orthopedic surgery unit is one of six units that were converted to units dedicated to COVID-19 patients. As of December 18, 2020, four different Winnipeg hospitals have been managing 120 critical care beds.
  • Guidance on Flow of Patients: The Public Health Agency of Canada advises that transfer within and between facilities while patients are suspected to be infectious should be avoided unless medically necessary. In Manitoba, where patients have recovered from COVID-19 infection after having been cohorted (i.e., in the Red Zone with other COVID-19 confirmed cases) can be moved into the Green Zone (within the hospital). For unconfirmed COVID-19 cases, Alberta Health Services note that criteria should be established to move suspect patient who test negative to another space in the facility.
    • Designated Hospitals: Saskatchewan divided the province into four regions with plans for a mix of COVID-19, non-COVID-19, and mixed hospitals based on a staged response to increased COVID-19 demand in a given geographical area. Island Health[1] (BC) has a regional strategy for cohorting patients such that three facilities have been designated as cohort hospitals. Patients are allocated to one of the facilities according to their geographic location and the medical orders for scope of treatment designation (MOST).

Ontario Scan

• Cohorting Principles: Guidance from the Ontario Medical Association (OMA) (May 2020):
  • Designated Hospitals: Designation of COVID-19 hospitals must occur in a phased approach, recognizing that the number of designated hospitals will increase as the number of cases increases in the province.
  • Spaces and Patients Should Be Segregated and Cohorted: Segregating spaces and cohorting patients according to COVID-19 status will be particularly important to enable the safe ramping up of deferred services in hospitals for non-COVID-19 patients while COVID-19 patients are still receiving care in the same facility. Segregating non-COVID-19 patients must be based on accurately identifying confirmed COVID-19 patients from those who may not have COVID-19.
  • Testing: Widespread point-of-care testing will allow for clearer distinctions between areas and patients by COVID-19 status.
• Guidance on Settings: From the OMA:
  • Designating Non-COVID-19, Suspect, and COVID-19 Areas from Admission to Discharge: Designating these areas includes the principle of “three zones and two channels”, which refers to the division of non-COVID-19, suspect, and COVID-19 areas, plus the creation of two separate channels for medical staff and patients to walk through. Designating patients also involves implementing a colour system for three zones throughout all areas of hospital: red (COVID-19 area), yellow (COVID-19 suspected area), green (non-COVID-19 area).⁹
  • Cohorting COVID-19 Patients by Units and by Floor: Cohorting patients involves the separation of COVID-19 patients and non-COVID patients, and further, cohorting among COVID-19 patients (i.e., separation of patients suspected with COVID-19, including those waiting for test results, from those patients confirmed to have COVID-19 [i.e., COVID-19 units and COVID-19-positive units]). COVID-19 patients can be further sub-cohorted, such as pregnant women, patients waiting for quarantine period to end, etc.

Individual peer-reviewed articles and review articles were identified through PubMed, the Cochrane Library, and Google Scholar. Grey literature was identified through Google and relevant government websites. The search was limited to English sources and therefore may not capture the full extent of initiatives in non-English speaking countries. Full-text results extracted were limited to those available through Open Access or studies made available to the Ministry by our partners.

The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers as the pandemic continues. The following members of the Network provided evidence synthesis products that were used to develop this Evidence Synthesis Briefing Note:

• Evidence Synthesis Unit, Research Analysis and Evaluation Branch, Ministry of Health. February 26, 2021.