Outbreak Response: Cohort Unit Design to Protect Residents, Staff, and Visitors

ECRI and Annals of Long-Term Care: Clinical Care and Aging (ALTC) have joined in collaboration to bring ALTC readers periodic articles on topics in risk management, quality assurance and performance improvement (QAPI), and safety for persons served throughout the aging services continuum. ECRI is an independent, nonprofit organization improving the safety, quality, and cost-effectiveness of care across all healthcare settings worldwide.

During an outbreak in an aging services organization, cohorting—when done correctly and in conjunction with other infection prevention and outbreak response practices—can greatly enhance the organization’s ability to prevent and control the spread of infection, along with concurrent gains in maintaining operations while minimizing risk to residents and staff. However, one size does not fit all providers. Although effective cohorting practices for a given infectious disease are generally consistent from one aging services organization to the next, the practical implementation can differ depending on the provider’s building layout and design, among other factors.

Building design and layout can help to inhibit or promote incidents and adverse events. Poor design of cohort units can undermine infection prevention and control efforts during an outbreak. The adage “form follows function” conveys the idea that we should design things to support the functionality we want to achieve. When we fail to do so, the opposite often happens—design determines function, often with suboptimal results.

It is important to establish policies for cohorting before they are needed rather than after an outbreak begins. To implement condition-driven cohorting, some states use a color-coded scheme. For example, Pennsylvania uses a green, yellow, and red color-coded scheme to cohort residents during the COVID-19 pandemic. The scheme is based on the resident’s test results and exposure status.¹ To provide practical illustrations of cohorting concepts discussed in this white paper, we will use the following zones to indicate the three primary cohort units that are beneficial in outbreak response:

• Green Zone: Nonexposed-resident care zone
• Yellow Zone: Quarantine zone to monitor those who are at risk for developing the infection
• Red Zone: Isolation zone for those who are known to have the infection

For example, Figure 1 demonstrates how cohort units can be designated in a facility. ECRI has also published a patient safety document “Strategies for Conducting SARS-CoV-2 Testing Based on Cohorting for Infectious Outbreak” which discusses virus testing for SARS-CoV-2 in aging services when using a red, yellow, and green zone cohorting strategy based on infection exposure risks. The document suggests that an organization should consider placing signs in the green zone at entrances to yellow zones indicating that only designated personnel are allowed beyond that point. See Door Sign for Infection Control Cohorting: Designated Personnel Only for an example (Available at www.ecri.org/components/CCRM/Documents/SPT/SafEnv/SafEnvPol48.pdf).

Effective cohorting goes beyond simply putting people with similar conditions together in the same unit. Other layout and design elements make physical cohort units more effective. These include design elements such as the following:

• Entrances and exits to the cohort units, including internal and external
• Personal protective equipment (PPE) donning and doffing rooms with appropriate disposal containers
• Infection prevention and control elements like handwashing stations, waste receptacles, clean and soiled utility areas, and others
• Environmental mechanical systems such as heating, ventilation, and air-conditioning (HVAC)
• Support service corridor access and workflow to help prevent exposure to support service staff and avoid bringing potentially infectious waste through yellow and green zones
• Interior finishes such as hard surfaces vs cloth surfaces, which can affect both the length of time that a virus exists and can infect others, and the disinfecting practices required for each surface

As provider organizations develop cohort unit plans as part of their larger infection control and emergency planning and response programs to address outbreak-related hazards, elements such as those listed above should be taken into consideration when identifying locations for isolation and quarantine areas. The ability to section an area off, proximity to other stakeholder populations, anticipated numbers of necessary beds, internal and external ingress and egress points into the area, layout, and availability of equipment and facilities to support other bundled practices that are care-critical to safety and outbreak response are all important decision-making factors in planning for and executing effective cohorting.

The number, location, and layout of PPE donning and doffing rooms—even those temporarily set up during an outbreak—are important considerations. Establishing a donning room near to, but separate, from the airlock or anteroom can also be an excellent layout strategy when space does not allow for large anterooms attached to resident rooms or units. This approach can accommodate one-way flow into the containment unit (separate from the exit) and avoids donning and doffing in the same space, which increases infection transmission risks.² By contrast, doffing rooms should not be separated from the containment unit due to the high risk of spreading contamination from the containment unit.

Thinking about traffic flow in a room where staff will remove soiled PPE is essential for the containment and source control of the pollutant or pathogen. Wherever possible, planners should strive to set up a one-way flow in the doffing room, moving from contaminated to clean, or hot to cold. Staff then move into a clean or cold area where they can redress if necessary, wash their hands, and obtain any clean PPE, if needed, before exiting the doffing area (see Figure 2).

The donning room should be of proper size and shape to facilitate, not hinder, the donning of PPE and be designed to allow storage and supply of clean PPE. The space should be large enough to include a safety officer that observes and informs the proper placement and donning sequence of specified PPE, which will depend on the specifics of the contaminated environment the personnel will enter. The Centers for Disease Control and Prevention offers several posters illustrating common PPE donning and doffing sequences, as well as posters illustrating dos and don’ts of facemask and respirator use, that organizations can print and post in their donning and doffing rooms.

The exit or doffing anteroom should be of proper size and shape to facilitate the doffing of PPE, again with proper observation space, to enable a proper PPE removal sequence. Most exposures take place during doffing; therefore, planners should thoughtfully consider space, layout, and ergonomics.

Negative-pressure anterooms.
Depending on the threat or the pathogen’s behavior, it may be advisable to establish an airlock anteroom area before the entrance and at the exit of an isolation or quarantine unit. This may be carried out by installing temporary barriers. Examples include infection control risk assessment for construction prefabricated or purpose-built portable barriers, creating a “two-door” vestibule and a separate exit of the same type. This approach helps contain pollutants and maintain pressure gradients, which is especially important if negative-pressure areas are needed to address airborne threats. These types of anterooms can also help to create staging areas for the flow of materials, services, and supplies like meals and laundry into cohorting zones. This helps minimize exposure risks for staff not directly assigned to the red or yellow zones.

PPE waste, trash, and debris.
The volume of soiled PPE and waste containers should be carefully considered. Containers with lids can help prevent accidental access by others when in the space or when transporting the container for disposal. However, lids should be opened in a touchless manner when possible. When the container liners are removed and replaced, care must be taken to avoid aerosolizing contaminants. When trash or debris exits the containment area, it should follow the shortest path (to avoid contaminating clean areas) to its designated holding area to await proper pickup for final disposal. Ideally, trash and debris exit the containment area directly into the designated holding area. The organization may consider exterior routes for moving contaminated materials if the building and site design permit it. Depending on the nature of the threat, frequency of trash and debris pickup may need to be increased. Staff responsible for those activities must be well versed in safely performing them to avoid becoming a vector of contamination throughout the facility.

Pressurization, other HVAC issues, and high-efficiency particulate air (HEPA) filtration are important considerations. Although HEPA filters with a minimum efficiency reporting value of 13 or better are at least 99.97% efficient at filtering 0.3 μm mass median diameter particles in standard tests,³ not all HVAC systems can handle the pressure drop caused by such an efficient filtration system. Although two air changes per hour (ACH) is the recommended minimum in health care patient or resident rooms, the American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends⁴ increasing the air exchange rate (eg, to 6 ACH) in the face of an infectious agent such as COVID-19, making it even more important to maintain sufficient air volume and air exchanges. Therefore, increasing fresh air intake is critical when installing HEPA filters.

As we have learned during the COVID-19 pandemic, our aging services care and service environments have not always been designed to support enhanced infection control and outbreak response needs, particularly the workflows needed to cohort and provide care to residents. Key layout and design issues to consider in order to support effective workflows for outbreak response and infection prevention include:

• sinks and handwashing stations, with adequate surfaces near the sink;
• alcohol-based hand rub locations;
• clearly marked soiled and clean utility locations;
• PPE storage and distribution locations, including PPE donning and doffing locations; and
• infectious waste collection and storage locations.

Simulation is a highly effective tool for planning and testing layout and design to ensure that they facilitate optimal workflows. Simulation may be performed in situ or virtually. In situ simulation provides real-world contextuality and gives individuals and teams authentic learning experiences in their place of daily work.⁵ In containment unit design, in situ simulation is of paramount importance. It helps identify obstacles and challenges that, in the design phase, may not be apparent until the environment is built, when it is too late to make changes to maximize the effectiveness of the workflow. When an existing space is renovated, temporary barriers, or even tape on floors representing walls and cardboard boxes for furnishings, may be used in the design phase to simulate the future environment, as designers and clinicians observe workers moving through mission-critical activities, such as donning and doffing PPE. This makes it possible to address issues before the design is finalized (eg, poor workflow that allows clean ingress and egress to cross with contaminated ingress and egress, sharp edges that may tear PPE).

In new construction, virtual simulation that shows workers moving through the design may be employed to identify similar challenges. Ideally, planners use a combination of virtual and in situ simulation of workflow and performance of mission-critical activities, like donning and doffing, to arrive at the ideal conditions for the final design of the containment unit and its supporting utilities.

During outbreaks, cohorting can greatly enhance an aging services organization’s ability to prevent and control the spread of infection among residents, staff, and visitors. While poorly designed cohort units can undermine infection prevention and control efforts and pose transmission risks, well-designed cohort units promote a system’s thinking approach, facilitate optimal care and services, and increase flexibility and resilience.

Aging services organizations must establish policies for cohorting before they are needed. Whether implementing cohort units in an existing building or forecasting cohorting needs when undertaking new construction or major renovations, the organization must analyze cohort unit siting and layout, utilities, equipment, supply management, PPE donning and doffing, waste disposal, and workflow. Modular architecture may help provide the flexibility and resilience necessary to respond to outbreaks, but this option is most cost-effective when considered prospectively, during construction and major renovations.

Cohort units may require a lot of planning, money, time, and other resources. But when combined with other outbreak response practices, effective cohorting helps prevent the devastating harm that can result from infection transmission within and outside the organization. By meeting the needs of individual residents and optimizing efficient use of space, staff, and resources, cohorting also helps maximize facility operating potential during challenging times.

To read more practical aging services risk management suggestions to help your organization improve its outbreak response, download “Outbreak Response in Aging Services: Cohort Unit Design” at www.ecri.org/outbreak-response-in-aging-services.