Emergency Operations Centers and Incident Management Structure

Jeffrey L. Bryant, Daniel M. Sosin, Tim W. Wiedrich, and Stephen C. Redd


Public health emergencies are often complex, protracted, and can overwhelm public health systems typically staffed and equipped for routine operations. Recent US and international responses to polio eradication (2011–present), the Ebola virus disease outbreak in West Africa (2014–2016), and Zika virus disease in the Americas (2016–2017) required extended field operations and response structures to bring partners together in a coordinated effort. Applying the concepts of emergency management, including the use of Emergency Operation Centers (EOCs) and Incident Management Systems (IMS) can help national and subnational public health systems protect populations impacted by a public health threat (1). For the United States, the National Response Framework (NRF) outlines the common structures national, state, and local governments use to respond to natural disasters, public health, medical, and other emergency situations (2). The NRF includes roles, responsibilities, and legal authorities used by different agencies within the US government during a response and applies to national, state, and local governments.

National-level organizations in the United States, such as the Centers for Disease Control and Prevention (CDC) consider an “All Hazards” approach to preparedness and response because epidemiology expertise is needed in diverse response activities ranging from traditional infectious disease outbreak investigations to chemical spill and natural disaster responses. Although every public health response has unique considerations, a functional knowledge of emergency management principles can help field epidemiologists integrate effectively into national and subnational emergency response structures.

Emergency Management Programs

An organization’s Emergency Management Program (EMP) comprises both preparedness and response activities. Preparedness activities, such as exercises and training, can help prepare field epidemiologists for response operations. The EMP facilitates efficient, coordinated public health activities for the duration of a response. Most EMPs use a tiered level of activations; in the United States, these generally range from Level 3 (lowest activation level) to Level 1 (highest activation level). This flexibility enables an organization to right-size response operations to meet changing response requirements. Most national-level agencies in the United States use the following activation levels:

Box 16.1
National Emergency Management Components and Principles
  • Defined modular management structures that are scalable and flexible
  • Standardized national response doctrine, including common terminologies
  • Focus on communication, information management, and resource management
  • Importance of operating from one set of objectives and priorities
  • Understanding of joint limitations in a multipartner environment
  • Protection of agency’s legal authorities to conduct response operations
  • Optimization of unity of effort among partners under a single plan
  • Level 3 (lowest level): This level implies that, with modest augmentation, the lead agency or program can address the primary needs of the response. In the United States, many small natural disasters or environmental responses fall into this activation level. An example is the CDC response to the 2016 water contamination crisis in Michigan.
  • Level 2 (intermediate level): This level implies substantial augmentation is required for the lead agency or program to meet response requirements. For CDC, the response to the 2011 Japan earthquake, tsunami, and nuclear disaster was a Level 2 activation.
  • Level 1 (highest level): This level requires an agencywide response and often includes domestic and international partners. As an example, CDC has recorded four Level 1 activations: Hurricane Katrina (2005), influenza A (H1N1) pandemic (2009–10), Ebola virus disease outbreak (2014–2016), and Zika virus outbreak (2016–2017).

The demands and complexity of a response influence the transition between levels. It is common for a response to transition between levels as operations escalate and deescalate. For example, the 2016 Zika virus response evolved from activation of the EOC at Level 3 in late January 2016 to Level 2 by the first week in February, and to Level 1 a week later because the size, scope, and complexity of activities warranted an agencywide response for CDC (CDC, unpublished data). For the 2014 Ebola outbreaks, the EOC was activated at Level 3 in July 2014 and in August of the year moved directly to a Level 1 response (CDC, unpublished data).

In the United States, government entities respond to public health emergencies using the structures and guidance in the NRF, which by design are scalable and flexible to fit the full spectrum of emergency responses (2). Familiarity with the basic emergency management components and principles outlined in the NRF (Box 16.1) can help field epidemiologists integrate into response structures at national, state, and local levels.

Box 16.2
Scientific Response Section Task Forcesa
  • Epidemiology and surveillance
  • State coordination
  • Vaccine
  • Modeling
  • Environmental health
  • Laboratory
  • Medical care and countermeasures
  • International operations
  • Global migration and quarantine
  • Infectious diseases

aIndividual task forces might not be part of every Incident Management System structure.

EMPs organize response structures in different ways. In the United States, most national and state systems use the common organizational designations in the NRF, which characterize necessary response functions according to major systems. For example, the national transportation, communication, or public health and medical systems all have a place in the overall structure. For public health organizations, common elements of a response may include epidemiologic investigations, laboratory services, medical care, medical countermeasure (such as vaccines, antiviral, and antimicrobial drugs) distribution, public messaging and risk communications, and partner communication—all organized in a series of task forces or similar structures within an IMS. For example, CDC organizes these response elements under a Scientific Response Section (Box 16.2), and understanding the relationships between the task forces or structures can benefit field epidemiologists. Within the CDC response structure, the task forces include subject matter experts, operational coordinators, and evaluators; whether an epidemiologist is forward deployed to conduct field investigations or works in the Atlanta- based EOC, he or she will be assigned to a given task force for guidance, assistance, and direction.

In addition to subject matter expert– led task forces, other key positions, and teams fall under the Incident Manager and the CDC IMS structure (Box 16.3).

Box 16.3
CDC IMS Response Positions and Teams
  • Joint Information Center
  • Deployment Risk Mitigation Unit
  • Safety
  • Liaison Officers
  • Ethics
  • Chief Science/Health Officer
  • Policy
  • Medical Investigations Team
  • Security
  • Office of General Counsel
  • Associate Director for Science
  • Deputy Incident Manager(s)

National and subnational EMPs also typically have a professional cadre of emergency managers who conduct preparedness activities (e.g., training and exercises) and serve in response leadership roles including senior positions in planning, logistics, operations, situational awareness, resource management, and communications. In the US emergency management system, these cadres are referred to collectively as the General Staff.

Emergency Operation Center Activations
Box 16.4
Common Activation Triggers for Emergency Operations Centers
  • Requests for assistance from overwhelmed cities, states, or countries
  • Need for significant external partner coordination
  • High political or media interest expected
  • Need to coordinate risk communication messages with diverse response partners
  • Need for significant internal coordination (multiple agency programs involved)
  • New agents or known agents exhibiting different characteristics
  • Activation of other Emergency Operations Centers by external response partners

EOCs around the world are activated for public health responses when routine systems and structures become overwhelmed (Box 16.4). As an example, during the Ebola outbreak during 2014–2016, Liberia developed an incident management structure operating from its EOC to manage response activities (3). Activation of the EOC facilitates overall response operations by providing the working platform and resources to support response staff through established structures, capabilities, and procedures. The EOC also provides the opportunity to bring relevant response partners together to establish common objectives and strategies, thus creating unity of effort. Each year in the United States, many public health emergency responses are handled efficiently using state and local resources without the need for national assistance. When national assistance is required, it is scalable and flexible and can be provided in many forms ranging from remote epidemiologic consultations to on-the-ground field epidemiology work in addition to other response capabilities.

Field epidemiologists can accelerate integration into national, state, and local response operations by understanding how working in an EOC environment differs from routine program conditions. For most public health organizations, day-to-day routines and activities are insufficient to successfully manage an emergency response. In the emergency response environment:

  • Response staff work in a rapid-pace setting for extended periods of time.
  • Decisions are needed quickly within a context of ambiguous and incomplete information.
  • Hiring, acquisition, contract, and other business processes must be expedited.
  • Working relationships expand to include new and external response partners.
  • Tensions can arise between response requirements and normal, daily obligations.
Meeting State Expectations

In the US response system, there is a very strong relationship between the national response systems and the subnational (state and local) response systems. Although most state and local public health agencies use the standard NRF organizational structure, the state and local systems vary greatly in relation to activation triggers, authority, and autonomy. Successful response depends on a strong understanding of the incident management approach used in an individual state system, the field epidemiologist’s relationship with these state and local systems, and agreement on the role of the field epidemiologists in these jurisdictions.

State and Local Incident Management Environments

In the United States, most (76%) state health officials are appointed by the state governor. The remainder are appointed by other state agency heads, state legislatures, or commissions (4). These governance relationships influence the day-to-day and emergency operations of state health departments. State public health incident managers receive authority from their respective governing and policy bodies, and this authority affects the specific system functions within each state. States vary in relation to the autonomy and delegated authority of local public health: in about 30% of states, local public health departments are highly subordinated centrally to the state health department, and the remainder are decentralized (4). These organizational differences between centralized and decentralized structures influence coordination between state and local public health jurisdictions and, consequently, how IMS structures are established to manage public health emergency responses. When field epidemiologists deploy, operational performance can be optimized through attentiveness to key considerations in advance of arrival in the affected field area and during work in the field. Using the US model between national and state governments, the following two sections describe issues national field epidemiologists should consider when deploying to subnational jurisdictions.

Before Arriving in the Field

  • Determine whether the IMS in a state or local jurisdiction was triggered and is activated.
    • If triggered, identify the incident management and liaison officer and agree on the reporting requirements and operating authorities (chain of command) that exist within the national and state response structures.
    • If not triggered, identify who has leadership responsibility for the state response and review the reporting requirements and operating authorities (chain of command) that are in place within the national and state response structures.
  • Clearly define the goals that the state and national public health systems hope to achieve in the field.
  • Establish the frequency, communications channels, location, and format for progress reports and updates.
  • Establish who has decision authority for and custody of collected data. Determine whether the response will use national or state information technology systems and files.
  • Review the supplies, equipment, work space, information technology, and transportation assets needed and identify who (national or state) will meet those needs.
  • Define a process for developing and approving public information messages.
  • Determine who has the authority to release information and data and agree on the methods used for data release.
  • Review arrival dates, location, and work hours.
  • Determine how the field epidemiology position fits into the state or local response operations. These positions can be embedded within a state team or can operate independently. If embedded, understand the role, team member roles, reporting systems, and the chain of command.
  • Identify environmental and safety conditions that might affect the responder and the response (i.e., weather, clothing, and transportation).

During the Field Operations

  • As soon as possible after arrival, secure a briefing with the state incident manager or, if the IMS was not triggered, with other state leadership.
    • Request an incident briefing, summary of findings, and recommendations for a work plan. Remain open and unbiased to this information.
    • Review and revise the issues covered in the prearrival discussions to ensure they are current and appropriate to evolving situations.
    • Confirm the frequency, communications channels, location, and format for progress reports and updates.
  • Participate in the situational awareness and progress update meetings. If unable to attend, notify and provide leadership with a written summary of activities or information to update the group, if possible.
  • Consider state operational suggestions if they do not conflict with national policies or procedures. State officials will have a foundational understanding of the limitations and challenges for response within their jurisdiction, which will help optimize the response work.
  • Respect the authority of the state and its leadership. The state may choose a course of action that does not have unanimous approval for reasons specific to the state.
  • Conduct an exit briefing shortly before departure.
    • Review what was accomplished and what remains to be done.
    • Establish frequency and channels for future communication.
    • Establish a procedure for approval and publication of any postevent media releases, academic publications, and poster presentations.
National and International Complexities of Public Health Emergency Response

The United States has legislation that establishes the legal authorities and responsibilities of the national government to conduct emergency response operations. The Robert T. Stafford Disaster Relief and Emergency Assistance Act, enacted in 1988 and last amended in 2013 (5), is the authority the Federal Emergency Management Agency uses to deliver national-level assistance to state governments. Such authorities might not exist in every country, and field epidemiologists should work with the Ministry of Health or international partners, such as the World Health Organization, to understand how response operations fit into national government or international structures. This includes considerations involving data collection, data analysis, information sharing, and potential publications. It also could include issues involving custody of laboratory samples, specimen transport, and customs and border implications for shipping or receiving medical countermeasures. Taking time to understand the field epidemiologist’s role in the context of a specific response operation involving multiple levels of government could help sort through complex issues such as these. In addition, field epidemiologists should understand reach-back mechanisms to their national governments as another resource to help work through complex national or international situations.

Another aspect of field epidemiology is knowing what resources might already be in place at a deployed location. Domestically in the United States, national public health personnel are embedded within state and local public health agencies. Knowledge of and outreach to these other field staff can accelerate integration into local response operations. Similarly, when field epidemiologists deploy to another country, there might be response partners permanently assigned to specific locations that can equally accelerate integration into the response.

Unique Aspects of Epidemiologic Field Investigations During an Emergency Response
Box 16.5
Unique Aspects of Epidemiologic Field Investigations During an Emergency Response
  • Rapid information gathering enables near real-time decisions and interventions.
  • Scale and speed of response activities are paramount.
  • Parallel and simultaneous investigations must be coordinated within the larger response effort and within the existing Incident Management System structure to avoid duplication of effort.
  • Wide media coverage and political pressures should be managed effectively by an experienced spokesperson/team for the response.
  • Increased leadership attention may result in greater access to resources, potentially augmenting demands on reporting and coordination requirements.
  • Investigation results or interim results may be used immediately to influence decisions by senior leaders.

Although IMS was not designed specifically for outbreak responses or public health emergencies, it does provide a clarifying framework for reporting and organizing the investigative work of an outbreak response. The basic purpose and methods are the same for epidemiologic field investigations undertaken during large-scale public health emergencies and in smaller programmatic response events. When an epidemiologic field investigation is conducted as part of a larger public health emergency response, the context and situation differ from those in routine investigations, particularly in the urgency, speed, and scale of the investigation (Box 16.5).

Because field investigations during emergency responses must be designed to answer questions in a timeframe sufficient to inform near real-time decision-making and interventions, they can constrain the adequacy of standard data collection and information analysis procedures. The team lead or senior field epidemiologist must decide which initial operational questions are most important and prioritize investigative efforts to answer those questions first. Most responses also carry Director’s Critical Information Requirements, or the equivalent, which are determined early in response operations and can change as the response develops. The Director’s Critical Information Requirements immediately and automatically trigger notification of senior agency leadership (Box 16.6).

Large and complex emergency responses can involve many national and subnational agencies. Under such circumstances, the epidemiologic investigation must be integrated into the larger response structure. For emergencies and investigations occurring simultaneously in multiple locations, activities sometimes require additional coordination and communication in the field and with the epidemiologist’s parent agency headquarters. In addition, complex responses will also require additional time to prepare and present progress reports to responsible authorities and time to speak with and receive guidance from the parent agency headquarters.

Box 16.6
Examples of CDC Director’s Critical Information Requirements
  • Serious illness or injury in deployed CDC staff member
  • Identification of new routes of transmission for infectious disease agents
  • Unexpected infectious disease cases or clusters
  • Infectious disease cases or clusters in new geographic areas
  • Major genetic sequencing changes for infectious disease agents
  • Initial requests for deployment of CDC assets
  • New security threats to areas where CDC staff are deployed
  • Communicable disease outbreaks in temporary shelter populations

An epidemiologic field investigation during an emergency response also might attract intense media interest. Preparation is critical and should entail planning for the following:

  • A predetermined, experienced media spokesperson.
  • Coordination with other agencies and state and local officials.
  • Help from health communicators to plan what information and public messaging strategies should be presented.
  • Assurance that all personally identifiable information is protected according to applicable laws.

Greater interest by the media, local officials, and others can add additional coordination and information burdens but also can create opportunities to marshal greater resources than in a lower profile event. Response leadership might be able to deploy more epidemiologists, have access to more data management specialists, add communications specialists to the investigative team, and provide logistics experts to support the investigation.

Finally, epidemiologic field investigations conducted during emergencies often result in actionable findings that have immediate implications for the public health response. Examples include the influenza A(H1N1) pandemic response in 2009– 2010 that generated recommendations such as school closures and cancellations of large social gatherings, and the Ebola response in 2014–2016 that resulted in acceptable interventions for contact tracing, active case finding, and safe burial practices.


In the United States, national emergency management programs, including EOCs and incident management structures, have been refined during the past 40 years and today provide an efficient and effective system for responding to public health emergencies. Standardization of emergency management components and principles across national, state, and local jurisdictions creates a common foundation for both public health and emergency management professionals. Field epidemiologists can accelerate their preparation for and integration into public health response operations by understanding the basic fundamentals:

  • National governments can have unique response systems, and field epidemiologists should remain flexible and strive to quickly integrate into national or subnational operations.
  • Functional knowledge of emergency management principles can help field epidemiologists integrate effectively into national, state, local, and international emergency response structures.
  • In an emergency response environment, routine daily systems and processes are often inadequate because:
    • Response staff work in a rapid-pace setting for extended periods.
    • Decisions are needed quickly within a context of ambiguous and incomplete information.
    • Hiring, acquisition, contract, and other business processes must be expedited.
    • Working relationships expand to include new and external response partners.
    • Tensions can arise between response requirements and normal, daily obligations
  • State, local, and international response environments can vary greatly and preparation for deployments should include an understanding of specific jurisdictions’ structures and authorities.
  • Public health emergency responses can be complex, and national systems designed to respond to natural disasters might require modification to be used successfully in a public health emergency.
  • Because national-level staff might live and work in jurisdictions to which an epidemiologist deploys, these staff understand the unique considerations of those communities and can help with response operations.
  • The IMS was not designed specifically for outbreak responses or public health emergencies, but it does provide clarity and a framework for reporting and organizing the investigative work of an outbreak response.
  • When an epidemiologic field investigation is undertaken as part of larger public health emergency response, the context and situation differ from routine operations, particularly in the urgency, speed, and scale of the investigation.
  • Epidemiologic field investigations undertaken during emergencies often offer the opportunity for the results to affect a public health response immediately.
  1. CDC. CDC’s Emergency Management Program activities—worldwide, 2003–2012. MMWR. 2013;62:709–13.
  2. Federal Emergency Management Agency. National Response Framework, third edition.
  3. Pillai SK, Nyenswah T, Rouse E, et al. Developing an incident management system to support Ebola response—Liberia, July–August 2014. MMWR. 2014;63:930–33.
  4. Association of State and Territorial Health Officials. State health agency structure, governance, and priorities. In: ASTHO profile of state public health, volume 3. Washington, DC: Association of State and Territorial Health Officials; 2014:17–28.
  5. Robert T. Stafford Disaster Relief and Emergency Assistance Act, Pub. L. 93–288 (November 23, 1988), as amended.