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.
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