On October 21, 2020, the Center for Disease Control (CDC) published a new guidance for use by contact tracers that clarifies what had been a somewhat fuzzy definition of "close contact." The new definition increases the number of individuals presumed to have an exposure to COVID-19, and will significantly affect schools and workplaces since those presumptively exposed individuals will be asked to isolate for a period of 14 days.
The guidance, which can be found here now defines a "close contact" as:
"Someone who was within 6 feet [whether masked or unmasked] of an infected person for a cumulative total of 15 minutes or more over a 24-hour period* starting from 2 days before illness onset (or, for asymptomatic patients, 2 days prior to test specimen collection) until the time the patient is isolated."
The prior CDC guidance led some health authorities and others to define "close contact" to involve a single uninterrupted 15-minute exposure. The new guidance explains that the cumulative total over a 24-hour period means:
"* Individual exposures added together over a 24-hour period (e.g., three 5-minute exposures for a total of 15 minutes). * * * Factors to consider when defining close contact include proximity (closer distance likely increases exposure risk); the duration of exposure (longer exposure time likely increases exposure risk); whether the infected individual has symptoms (the period around onset of symptoms is associated with the highest levels of viral shedding); if the infected person was likely to generate respiratory aerosols (e.g., was coughing, singing, shouting); and other environmental factors (crowding, adequacy of ventilation, whether exposure was indoors or outdoors)."
It is not hard to imagine how one infected individual in a workplace who has a series of one or two minute interactions with other individuals over the course of a 24-hour period can add up to 15 cumulative minutes. Each individual that the person has "close contact" with must then self-quarantine, which can lead to a pyramid effect involving many other individuals.
Employers should continue to emphasize the importance of maintaining six feet of distance at all times for employees. If employees need to have a conversation, consider options other than face-to-face meetings, such as telephone or video conferencing. Six feet of distance appears to be the last line of defense for employers who just need to keep their businesses operating.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
