ARCHIVED WEBPAGE: This web page is available for historical purposes. CDC is no longer updating this web page and it may not reflect CDC's current COVID-19 guidance. For the latest information, visit CDC's COVID-19 home page.

Important update: Healthcare facilities
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Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
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Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Investigating and responding to COVID-19 cases in non-healthcare work settings

Investigating and responding to COVID-19 cases in non-healthcare work settings

Universal case investigation and contact tracing are not recommended. This guidance can be used for investigation of priority cases and notification of priority close contacts outlined in the Prioritizing Case Investigation and Contact Tracing for COVID-19 guidance.

Summary of Recent Changes

  • Removed or updated links to archived pages.
  • Added information about considering worker vaccination status.

Purpose: Workplaces can present unique challenges for COVID-19 investigation and public health action. Because many workplaces can be crowded settings, and many jobs involve a high level of interaction with the public, these settings can allow virus to spread easily among workers. The information on this page can be used for responding to individual cases and outbreaks in non-healthcare work settings.

Other relevant resources include:

Standards and guidance for responding to cases among workers and patients in healthcare settings:

OSHA Guidance for general workplaces:

Considerations for health departments for prioritizing non-healthcare workplace investigations:

Resources for some specific types of non-healthcare workplaces:


Many people spend a large portion of their days at work, often in  (less than 6 feet away from an infected person [laboratory-confirmed or a clinical diagnosis] for a cumulative total of 15 minutes or more over a 24-hour period) with other workers and the public. It is important to recognize and take action to prevent transmission of infectious diseases, including COVID-19, in the workplace. Workplace mitigation strategies include promotion of worker vaccination, exclusion of infected workers from the workplace, case investigation and contact tracing, optimization of ventilation, enforced indoor masking policies, physical distancing, and sanitation and cleaning. Reviewing and recognizing workplace factors (e.g., work practices, policies, and processes) and worker factors (e.g., demographics, social determinants of health, and language or literacy barriers) may help state and local health departments, as well as employers, identify circumstances that contribute to disease transmission within the workplace and in the community. In addition, certain workplace and worker factors may provide insight into how health disparities impact infection rates and disease outcomes.

Occupation and industry data collection during disease investigation

Collecting information about a person’s job (e.g., occupation and industry) during case investigation and subsequent contact tracing may facilitate early recognition of wider viral transmission and a potential workplace outbreak. Guidance for collecting these data can be found on the National Institute for Occupational Safety and Health (NIOSH) topic page Collecting and Using Industry and Occupation Data and in the Council of State and Territorial Epidemiologists (CSTE) Occupational Health Subcommittee  document Recommended Interim Guidance for Collecting Employment Information about COVID-19pdf iconexternal icon.

Workplace COVID-19 clusters should also be reported to public health authorities (PHAs) or Occupational Safety and Health Administration (OSHA) officesexternal icon by workers, employers, worker organizations, or healthcare providers, in addition to official case report investigation efforts. PHAs should consider proactively recommending that any employers in their jurisdiction notify them if they learn about ≥2 cases in workers who have been in close contact to a person with COVID-19 in a non-residential and non-healthcare worksite. For special work or living settings that are prone to rapid spread of disease, such as long-term care facilities, reporting is recommended for even just one case in a worker or resident.

The legal authority for communicable disease case investigation, including contact tracing lies with PHAs in state, local, and territorial health departments (SLTHDs). CDC encourages collaboration between employers and health departments in the investigation of workplace exposure to COVID-19. However, roles and responsibilities should be negotiated at the local level, given the authority and responsibility of the public health departments in disease control and given the level of interest and capacity of the employers.

Although many of the considerations and tools here are most applicable to responding to cases among workers who work in a fixed location, such as a factory or office building, it is also important to consider occupational risks that apply to mobile worker groups, such as transit workers, rideshare drivers, food delivery drivers, construction contractors, and workers (e.g., childcare providers, cleaners) who work in clients’ homes. It is also important to consider that disease transmission can spread in either direction between workplaces and communities.

PHAs should maintain clear communication pathways with local business communities and other organizations that work with employers and workers to help ensure that information about COVID-19 among workers is shared in a timely manner.

Considerations for State and Local Health Departments on Investigating Non-Healthcare Workplace Clusters of COVID-19

 General approach to investigating a workplace cluster

When COVID-19 cases are identified in a workplace, public health authorities (PHAs) should determine if an outbreak investigation is necessary. CDC encourages collaboration between employers and health departments in the investigation of workplace exposure to COVID-19; however, the legal authority for communicable disease case investigation lies with PHAs. While workplace investigations should follow the same general approach as other outbreak investigations, specific information can be helpful to consider in the work environment. Outbreak investigations may include four components:

  • Exposure, engineering, and work practice assessment, including assessment of worker vaccination access, acceptance, and uptake
  • Epidemiologic investigation
  • Medical record review
  • Employer policy and record review

These components provide insight in identifying who is at risk, modes of transmission, and worker and workplace factors that contribute to disease transmission and can help inform infection prevention and control recommendations to reduce COVID-19 transmission. Because every workplace is unique, each situation will dictate which investigation components are necessary to identify appropriate controls and disrupt transmission. CDC’s National Institute for Occupational Safety and Health (NIOSH), trade associations, unions, state-based occupational health programs, and academic occupational health programs can provide subject matter expertise for various industry sectors, as needed.

After COVID-19 cases are identified in a workplace, and it is determined that an outbreak investigation is warranted, a multidisciplinary investigation team should be established by the PHA, in collaboration with CDC if assistance is needed. This team may include qualified professionals with experience in the fields of:

  • Public health
  • Occupational safety and health (including industrial hygienists and engineers)
  • Infection prevention and control
  • Epidemiology
  • Medicine (occupational medicine, or if specialists are unavailable, general practitioners)

The team may also include other relevant practitioners, agencies, or stakeholders (e.g., agricultural agencies and veterinarians in the case of food processing facility outbreaks). Cultural liaisons may also be helpful to include if the workplace has a high proportion of refugees, immigrants, or other special populations within the workforce. After a team is formed, the investigation should begin in close consultation with officials from the facility including occupational health programs and unions or other worker organizations, if present in the workplace. If no union is present, it is important to include a worker representative in the investigation process to ensure all parties receive the same information. The team should follow the basic steps for conducting any outbreak investigation, but tailor their approach to incorporate principles that apply to the individual work environment. This includes developing a comprehensive set of questions based on knowledge of the industry and COVID-19.

The investigation team can learn about job-related characteristics associated with COVID-19 by reviewing information already available from case reports and interviews. This information can then be supplemented with employee records such as rosters that include occupational information (e.g., job tenure, job title), worker interviews or surveys, and review of occupational health policies and procedures.

Workplace outbreak investigation components

As mentioned above, specific information is available to consider for workplace environment safety. Components such as exposure, engineering, and work practice assessment; epidemiologic investigation; medical record review; and employer policy and record review may be included when conducting workplace outbreak investigations. Information about each component is provided below.

Exposure, engineering, and work practice assessment

Exposure assessment should identify potential pathways of exposure, assess the presence and use of workplace controls, and evaluate the capability of an employer to effectively implement additional controls needed to prevent further COVID-19 transmission. Identifying and controlling exposures to occupational hazards is the fundamental method of protecting workers. Traditionally, a hierarchy of controls has been used to help determine ways of implementing feasible and effective control solutions. During this component of the investigation, it is critical to enlist help from industrial hygiene, engineering, and infection control professionals who understand how to evaluate the workplace and implement effective procedures based on the hierarchy of controls.

The hierarchy of controls includes:

  • Engineering controls, such as
    • Modifying workstations or workflow to increase distance between workers
    • Enhancing and maintaining ventilation systems
    • Using physical barriers to separate workers from each other and clients (when applicable)
    • Providing accessible hand hygiene options (handwashing and/or hand sanitizer)
  • Administrative controls, such as
    • Developing and implementing vaccination policies that explain procedures for vaccinated and unvaccinated workers
    • Pre-shift symptom screening
    • Developing and implementing physical distancing policies and procedures for work areas and other areas where workers might congregate (e.g., break/dining areas, locker rooms, smoking areas, entrance/exits, parking lots)
    • Reviewing and revising procedures for cleaning and disinfecting surfaces within work areas and other areas, including appropriate scheduling of cleaning and disinfecting tasks and use of appropriate disinfection agentsexternal icon
    • Communicating with workers and training them on COVID-19 and workplace strategies to prevent infection, including information about how and why engineering, administrative, and personal protective equipment or source control measures are being implemented
    • Encouraging workers to wear a mask at work if the hazard assessment has determined that they do not require personal protective equipment, such as a respirator or medical face mask for protection, and depending on the level of transmission in your county
  • Personal protective equipment (PPE), which includes
    • Providing access to and training on the use of appropriate PPE based on an assessment of workplace hazards present in the facility
    • Potentially supplementing PPE usually worn for a given task with additional PPE for COVID-19 infection prevention

Epidemiologic Investigation

An epidemiologic investigation in the workplace is important because it helps to better define the characteristics of workers who contracted COVID-19; it can offer insight into risk factors for transmission, prevalence, and incidence of disease within the workplace. A workplace epidemiologic investigation may include:

  • Defining the worker population at risk:
    • Minimally, investigators should consider obtaining lists of all workers present at the workplace or in the work environment (e.g., construction site) during a defined time period (i.e., contact elicitation window as defined in the outbreak case definition).
    • At some workplaces, this may include workers employed by multiple companies (e.g., contractors, sub-contractors), workers who are responsible for performing a variety of tasks (e.g., production, transportation, customer service, food preparation, cleaning), and workers who may not be employed by the company but may have been physically present at the company during the defined period of interest (e.g., transportation and delivery services).
    • In addition, collecting information about key variables such as department or area of work, shift, and job tasks and titles is helpful so that attack rates for specific groups of workers can be calculated to determine the need for additional control measures.
  • Systematically identifying and documenting all known cases and contacts among the worker population at risk. This can be done by PHAs through comparing a list of reported cases with the list of workers at risk and by contact tracing for known cases. Additional information about contact tracing can be found on the CDC COVID-19 Contact Tracing website.
  • Interviewing cases and contacts in the workplace can use a standard questionnaire, which follows CDC guidance for case investigation and contact tracing. Questions asked in a workplace setting should address:
    • Vaccination status
    • History of symptoms of COVID-19
    • Known exposures to other confirmed or probable cases in and outside of the workplace (e.g., in the household or community)
    • General work practices
    • Workplace controls (including PPE), and any breaches in the controls that occurred prior to the case becoming infected
    • While in-person interviews are often used in outbreak investigations, during the COVID-19 pandemic, every effort should be made to interview workers by telephone or video conference instead of in-person to better protect investigation staff.
  • Developing and implementing systems and procedures to provide ongoing monitoring of workers at risk could include:
    • Vaccination status monitoring
    • Enhanced symptom and illness monitoring and record keeping to document all exposed and symptomatic personnel. This includes daily/pre-shift symptom screening performed by employee healthcare staff or contractors. An electronic monitoring and notification system can also be used to provide ways for employees to self-report and monitor symptoms through a website or mobile app, with alerts sent to a health professional.
    • Absenteeism monitoring with special focus on absences due to COVID-19-like-illness (CLI).

If an employer chooses to conduct enhanced symptom and illness monitoring, they should routinely and systematically review screening results. They should also have a referral process in place that will direct employees with signs or symptoms of CLI to the system established by local public health departments for further assessment. It is important to note that some workplaces might have a system already in place for employee monitoring, assessment, and testing. In these workplaces, employers should have systems set up to ensure all test results are reported to the appropriate PHAs to ensure proper follow up and investigation. In some cases, PHAs may have the right to access, monitor, and review all records.

Medical Record Review

Medical record review for a workplace cluster can include conducting medical records abstraction to assist with the epidemiologic component of the investigation. Individuals, organizations, and agencies that are covered entitiesexternal icon under the Health Insurance Portability and Accountability Act (HIPAA) must abide by HIPAA rules. However, HIPAA permits covered entities to disclose protected health information without authorization for specified public health purposesexternal icon. Records that PHAs may be able to access include:

  • Employee health records from in-house or contracted providers
  • Workers’ compensation records
  • Records from workers’ personal medical providers

Employer Policy and Record Review

 Relevant occupational health and medical policies and procedures to review include:

  • COVID-19 response plans
  • COVID-19 vaccination policies
  • Employee health screening
  • Health monitoring
  • Sick and medical leave policies
  • Telework policies
  • Return-to-work criteria
  • Training policies
  • Respiratory protection programs
  • Standard operating procedures
  • Procedures for enforcing policies

Other employer records that may be needed to supplement the investigation include:

  • Facility specific floor plans or diagrams
  • Process and job task descriptions
  • Photographs or videos
  • OSHA logsexternal icon
  • Employee rosters
  • Employee vaccination records
  • Shift schedules
  • Attendance records

In some cases, PHAs may also request access to records of client interactions (e.g., appointment or site visit calendars) in order to identify non-worker workplace close contacts of cases.

In Summary

After this information is collected and analyzed, the team should provide site-specific recommendations to workplace officials. These recommendations should be shared with the requester of the cluster investigation and any unions present within the workplace. The team can also provide specific training or expertise to the employer as needed. Recommendations and training should be based on best practices followed by related industries and provided by OSHA, CDC, and state and local health departments for COVID-19.