CDC redefines COVID-19 close contact exposure to total time spent in 24 hours, and updates case investigation and contact tracing

Oct. 22, 2020

On Wednesday, the Centers for Disease Control and Prevention (CDC) changed their ‘close contact’ exposure time from spending a solid 15 minutes within six feet of someone who tested positive for coronavirus to a total of 15 minutes or more to include shorter but repeated contacts that add up to 15 minutes over a 24-hour period, reported the CDC. 

The CDC reported total US cases at 8,249,011 with 60,426 new cases, total deaths at 220,362

and 863 as of October 21. The updated definition can be found here

Case investigation and contact tracing, a core disease control measure employed by local and state health department personnel for decades, is a key strategy for preventing further spread of COVID-19. Immediate action is needed. Communities must scale up and train a large workforce and work collaboratively across public and private agencies to stop the transmission of COVID-19. 

Certain core principles of case investigation and contact tracing must always be adhered to:

Case investigation is part of the process of supporting patients with suspected or confirmed infection.

In  case investigation, public health staff work with a patient to help them recall everyone with whom they have had close contact during the timeframe while they may have been infectious.

Public health staff then begin contact tracing by warning these exposed individuals (contacts) of their potential exposure as rapidly and sensitively as possible. 

To protect patient privacy, contacts are only informed that they may have been exposed to a patient with the infection. They are not told the identity of the patient who may have exposed them. 

Contacts are provided with education, information, and support to understand their risk, what they should do to separate themselves from others who are not exposed, monitor themselves for illness, and the possibility that they could spread the infection to others even if they themselves do not feel ill. 

Contacts are encouraged to stay home and maintain social distance from others (at least six feet) until 14 days after their last exposure, in case they also become ill. They should monitor themselves by checking their temperature twice daily and watching for cough or shortness of breath. To the extent possible, public health staff should check in with contacts to make sure they are self-monitoring and have not developed symptoms. Contacts who develop symptoms should promptly isolate themselves and notify public health staff. They should be promptly evaluated for infection and for the need for medical care. 

Case investigation and contact tracing is a specialized skill. To be done effectively, it requires people with the training, supervision, and access to social and medical support for patients and contacts. Requisite knowledge and skills for case investigators and contact tracers include, but are not limited to: 

·        An understanding of patient confidentiality, including the ability to conduct interviews without violating confidentiality (e.g., to those who might overhear their conversations)

·         Understanding of the medical terms and principles of exposure, infection, infectious period, potentially infectious interactions, symptoms of disease, pre-symptomatic and asymptomatic infection

·         Excellent and sensitive interpersonal, cultural sensitivity, and interviewing skills such that they can build and maintain trust with patients and contacts

·         Basic skills of crisis counseling, and the ability to confidently refer patients and contacts for further care if needed

·         Resourcefulness in locating patients and contacts who may be difficult to reach or reluctant to engage in conversation

·         Understanding of when to refer individuals or situations to medical, social, or supervisory resources

·         Cultural competency appropriate to the local community

·         Case investigation and contact tracing is part of the process of supporting patients and warning contacts of exposure in order to stop chains of transmission. 

Given the magnitude of COVID-19 cases and plans to eventually relax mitigation efforts such as stay at home orders and social distancing, communities need a large number of trained case investigators and contact tracers. Case investigators need to quickly locate and talk with the patients, assist in arranging for patients to isolate themselves, and work with patients to identify people with whom the patients have been in close contact so the contact tracer can locate them. The actual number of staff needed is large and varies depending on a number of factors including but not limited to: 

·         The daily number of cases

·         The number of contacts identified

·         How quickly patients are isolated, and contacts are notified and advised to stay home, self-monitor, and maintain social distance from others

·         The time to start building the trained workforce is now.

·         Time is of the essence.

·         Identifying contacts and ensuring they do not interact with others is critical to protect communities from further spread. If communities are unable to effectively isolate patients and ensure contacts can separate themselves from others, rapid community spread of COVID-19 is likely to increase to the point that strict mitigation strategies will again be needed to contain the virus.

·         Case investigators and contact tracers need to:

·         Immediately identify and interview people with SARS CoV-2 infections and COVID-19 (i.e., disease)

·         Support isolation of those who are infected

·         Warn contacts of their exposure, assess their symptoms and risk, and provide instructions for next steps

·         Link those with symptoms to testing and care 

Based on current knowledge, a close contact is someone who was within 6 feet of an infected person for a total of 15 minutes or more starting from 48 hours before illness onset until the time the patient is isolated. They should stay home, maintain social distancing, and self-monitor until 14 days from the last date of exposure.  

Appropriate engagement with infection control and occupational health programs is recommended. Priority settings include: 

·         Health care facilities including long-term care facilities

·         Group home/board

·         Homeless shelters

·         Federal, state and local correctional facilities

·         Crowded, multigenerational housing 

In addition to healthcare workers, it is important to assess interactions between residents and all staff, including but not limited to activity coordinators, food service staff, and sanitation management. Transitional case management plans should be put in place for patients in isolation and contacts who are separated for monitoring. Management plans should also be created for transitioning from one setting to another, such as transitions from hospitals to acute or long-term care facilities or home isolation, or from prison and jail to parole and probation. 

The adoption of emerging technologies that can assist private and public health practitioners with client communication, medical monitoring, and strategies to amplify case investigation and contact tracing may greatly help with scaling up these activities as needed.  

·         Ongoing monitoring and assessment of case investigation and contact tracing efforts will be needed.

·         Public health agencies and their partners will need to monitor some key components of their programs to improve performance as needed. Potential metrics routinely reviewed could include the following process and outcome measures:

·         Case interviewing: Time to interview from symptom onset and from diagnosis; proportion interviewed; median number of contacts elicited; proportion with no contacts elicited.

·         Contact notification: Proportion of contacts notified; time from first potential exposure to notification.

·         Contact follow-up: Daily proportion of contacts whose status is evaluated; proportion of contacts with symptoms evaluated within 24 hours of onset of symptoms; proportion of contacts who complete their full self-monitoring period

·         Contact tracing efficacy: Percent of new COVID-19 cases arising among contacts during self-monitoring period. 

CDC has the guidance

More COVID-19 coverage HERE.

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