When COVID-19 swept into New York City in early 2020, it did not just test hospital capacity; it stress-tested the very systems designed to manage crisis. At the Mount Sinai Health System (MSHS), the pandemic became a proving ground for a new kind of incident management: one that would ultimately move beyond traditional command-and-control models toward a more flexible, clinically integrated approach.
The Limits of Traditional Command
MSHS, like most U.S. healthcare institutions, rooted its emergency framework in the Incident Command System (ICS), a model originally developed in the fire service during the 1970s and later formalized under FEMA’s National Incident Management System (NIMS) (FEMA, 2017). In healthcare, this evolved into the Hospital Incident Command System (HICS), designed to bring structure and hierarchy to emergency response in that setting. However, during a real-world crisis, especially one as prolonged and complex as COVID-19, frameworks do not always conform to such rigid hierarchies.
Healthcare leaders quickly encountered familiar challenges: staff unfamiliar with ICS roles, communication delays, duplicated decision-making, and a system that struggled to keep pace with rapidly changing conditions. In highly dynamic healthcare environments, traditional HICS structures can become cumbersome. One can make the case that they are better suited to predictable scenarios than to the uncertainty of a global pandemic.
These limitations are well documented While ICS has been successfully used in public health responses by the CDC during SARS and H1N1 (Papagiotas et al., 2012), research highlights persistent barriers in healthcare settings, including gaps in training, oftentimes leading to apprehension and resistance to participation, limited adoption of the formalized and unfamiliar structure, and misalignment with clinical workflows (Tsai et al., 2005). The model’s hierarchical and mechanistic design can slow decision-making in fast-changing scenarios, where improvisation and rapid adaptation are essential. Hospitals, by contrast, operate more organically, with interdependent teams and fluid communication patterns, making strict ICS structures difficult to sustain under prolonged stress.
A System Tested in Real Time
Ironically, MSHS had just completed a major overhaul of its emergency management infrastructure when COVID-19 hit. The revised structure included operational modifications to a system-wide Emergency Operations Center (EOC) and site-level Incident Management Teams (IMTs), but it had not yet undergone full-scale testing.
Instead, the validation came in real time.
As patient volumes surged and operational pressures mounted, the system adapted on the fly. One of the earliest shifts was moving away from a single Incident Commander to a Unified Command Group (UCG). The UCG included senior clinical and operational leaders who could collectively process information and make decisions at the speed the crisis demanded. This change marked a fundamental shift: from centralized command to collaborative leadership.
At the same time, New York City became the epicenter of the U.S. outbreak, with surging emergency department visits, hospitalizations, and mortality placing unprecedented strain on bed capacity, supply chains, mortuary capacity, and staffing. MSHS’s newly designed system, originally intended for a gradual rollout and validation, was activated immediately. Site IMTs and the system EOC had to synchronize operations across eight hospitals, a medical school, and hundreds of ambulatory practices. This real-world stress test exposed coordination challenges but also accelerated innovation, forcing rapid refinement of communication pathways, leadership structures, and decision-making processes.
The ESF/CSF Model: An Organic Approach
The most significant innovation to emerge from this period was the development of the Essential Support Function (ESF) and later, Clinical Support Function (CSF) framework. Rather than assigning staff to unfamiliar ICS roles and requirements during a crisis, the ESF/CSF model aligns emergency responsibilities with existing operational roles. The same leaders who manage departments during “blue-sky” (normal) operations continue to lead those areas during “black-sky” (crisis) events.
This approach offers several advantages:
- Continuity: Staff operate within familiar roles, reducing confusion and stress.
- Speed: Decisions are made by subject-matter experts already embedded in operations.
- Scalability: Functions can scale up or down based on the severity of the incident.
- Integration: Clinical and operational domains unified under a single framework.
Today, MSHS operates with 22 ESFs and 35 CSFs, collectively representing the full enterprise, from supply chain and communications to every clinical specialty. There is ongoing reassessment, with some structural entities combining while others divide into separate entities as the system structure evolves. This posture enables continued, accurate, and ongoing representation of the overall system and its sites.
The model evolved from a key realization: that system-level coordination was more effective when engaging directly with service line leaders rather than filtering information through multiple layers of site-based ICS roles. By organizing response functions around existing departments, the system reduced redundancy and improved clarity. The organization first introduced ESFs to focus on operational support functions, followed by CSFs to fully integrate clinical services. This progression enabled a comprehensive “system capture” of both clinical and non-clinical resources, ensuring that all personnel could be rapidly mobilized, reassigned, or scaled up or down in response to real-time needs.
A cornerstone of the ESF/CSF model is its scalability. More specifically, depending on the scope of the incident, this system is highly adaptable so that the EOC or site IMTs can adjust ESF/CSF mobilization as needed. MSHS has created a system of severity levels and activation criteria that provide triggers and guidance for expanding EOC activation and footprint. The MSHS incident severity levels provide high-level activation criteria and guidance for consideration based on the size, scope, and potential impact of an incident. To support this, MSHS has developed a comprehensive Activation and Response Algorithm that guides leadership decision-making from initial incident notification through demobilization operations. Furthermore, the Activation and Response Algorithm is unique in that it strikes a critical balance between differentiating site/system strategies and tactics, while simultaneously emphasizing critical escalation criteria supported by continuous, ongoing thresholds for system support.
Technology as a Force Multiplier
The pandemic also accelerated the adoption of digital collaboration tools. Cloud-based platforms enabled large-scale coordination meetings that would have been impossible in a physical EOC. Daily system-wide briefings, sometimes held twice a day, brought together hundreds of leaders across hospitals, ambulatory sites, and administrative units. These briefings became the backbone of situational awareness, supported by concise, rapidly distributed reports and guidelines.
What began as a necessity quickly became a strategic advantage. Social distancing requirements during the pre-vaccine phase made traditional in-person command centers impractical, driving rapid adoption of virtual platforms. These tools allowed hundreds of participants to join coordination calls simultaneously, eliminating physical space constraints and enabling broader engagement across the enterprise. The ability to convene ESF and CSF leads in real time significantly enhanced information sharing, alignment, and decision-making, and became a critical enabler of the evolving incident management framework.
Bridging Emergency Management and Business Continuity
Another key evolution has been the continued integration of emergency management and business continuity planning. The development of these plans and operational frameworks within each ESF and CSF provides the foundation for operational resilience during both crisis and day-to-day functions. The result supports seamless transition between routine operations and emergency response, and less of a switch than a shift in posture.
This integration ensures that emergency response plans and business continuity strategies are developed in parallel and fully synchronized. Plans are developed at both the site and system level, creating a unified framework for action. This alignment enhances preparedness and ensures that, whether responding to an acute incident or sustaining long-term operations, the organization operates with a common language, structure, and set of expectations.
Transition from Pandemic to Normal Practice
As the situation stabilizes, the system’s long-term resilience comes into focus. For MSHS, the ESF/CSF model proved its value during every subsequent activation, including most recently, a major labor disruption in 2025–2026. In that context, the framework enabled rapid redistribution of clinical staff, efficient patient decompression, and continuity of care despite significant workforce challenges by providing the framework and conditions for discussion, strategy assessment, decision-making, and operationalization. The CSF structure already maps each clinical service line, giving leadership immediate visibility into both needs and available resources.
This capability is particularly important during staffing disruptions, where maintaining healthcare delivery requires a dynamic reallocation of personnel and services. The ESF/CSF structure enabled leaders to identify underutilized resources quickly, redeploy staff from affected service lines, and prioritize critical care areas. The model’s flexibility ensured that operational and clinical decision-making remained synchronized, even under sustained pressure, reinforcing its effectiveness across different types of crises beyond infectious disease response.
A Model of Response for Modern Healthcare Systems
MSHS’s experience highlights a broader lesson for healthcare systems: crisis management cannot rely solely on rigid hierarchies or imported frameworks. It must reflect the realities of complex, interdependent, and constantly evolving clinical operations. By blending the structure of ICS with a more organic, role-based approach, the MSHS Incident Management System has created a model that is both disciplined and adaptable.
The recognition of real challenges, confusion over ICS roles, duplication of effort, and misalignment between site and system operations ultimately drove both the creation and continued evolution of this system. By redesigning the framework around existing leadership roles and workflows, MSHS created a structure that enhances situational awareness, accelerates decision-making, and improves communication across the enterprise. The result is a unified, scalable model that not only withstands crisis conditions but also strengthens the organization’s overall resilience, offering a practical blueprint for other healthcare systems and public health agencies seeking to modernize their emergency management approach.
Citations
Federal Emergency Management Agency. (2017). National incident management system (3rd ed.). U.S. Department of Homeland Security.
Papagiotas, S. S., et al. (2012). From SARS to 2009 H1N1 influenza: The evolution of a public health incident management system at CDC. Public Health Reports, 127(3), 267–274.
Tsai, M. C., et al. (2005). Implementation of the hospital emergency incident command system
during an outbreak of severe acute respiratory syndrome (SARS) at a hospital in Taiwan, ROC.
Journal of Emergency Medicine, 28(2), 185–196.
