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The following was information given from Dr. Audrey Pettifor (Gillings School of Global Public Health):


“NC DPH recommends the following definition for reporting clusters of COVID-19 in workplace, educational, and other community settings. A cluster is defined as “a minimum of 5 cases with illness onsets or initial positive results within a 14-day period AND plausible epidemiologic linkage between cases. Local health departments should verify that cases were present in the same setting during the same time period (e.g., same shift, same classroom, same physical work area); that the timing fits with likely timing of exposure; and that there is no other more likely source of exposure for identified cases (e.g., household or close contact to a confirmed case in another setting).”

Dr. Pettifor’s reading is of this is that a cluster would mean 5 or more cases within the 14 days and that are likely in the same lab or office and they are working the same shifts (so people working on alternate days or who aren’t in contact with the infected person would likely not be considered a contact). She does not think just being in the same building or even floor would usually be included. Her understanding for case investigation is they work out from the case—so they would test people in closest contact—if those people were positive they might move out from there to others in the lab not in close contact or people on the same floor and if positives there then maybe test more in building etc.

Contact tracing for employees (including graduate student employees) is handled by Employee Occupational Health, and more information is on the Carolina Together website:

UNC Employee Occupational Health is handling all contact tracing for faculty and staff (this includes graduate students in their capacities as employees). The University Employee Occupational Health Clinic (UEOHC) is specifically responsible for identifying close contacts in the workplace. If a UNC-CH employee tests positive, any close contacts they have outside of work are contacted by their county health department. Campus Health reports all positive tests they receive for student employees to the UEOHC.

Contact tracing is performed for all COVID-positive employees. Employees are interviewed to see if their interactions with other faculty, staff or students would meet the definition of a community contact and those UNC-CH employees are then contacted. UNC-CH uses up-to-date contact tracing definitions from the NC DHHS and the CDC—at this time, the definition of a close contact as anyone who is within 6-feet of another person for more than 15 minutes. Of note, even if both parties were wearing masks the entire time, they may still consider them a close contact depending on the workplace setting. In healthcare or laboratory setting, where the employees are both staff wearing employer-provided masks, they may not be considered a close contact if both parties are wearing masks. In other settings where both parties are perhaps wearing lower grade masks or cloth face coverings, the UEOHC may consider them a close contact even if both parties were wearing masks. Once a close contact is identified, they are asked to self-quarantine for 14 days.

Despite initial concerns, there is no evidence of occupational COVID transmission on the UNC-CH campus through HVAC systems, buildings or surface contamination. Overwhelmingly, UNC-CH employees who have tested positive for COVID have a clearly identified exposure to a COVID-positive community contact (e.g., household member, close contact). Due to UNC-CH faculty, staff, and student compliance with community standards, over 50% of contact tracing has resulted in no additional occupational COVID-related absences beyond the initial positive case.


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