Recently, the CDC updated the definition of “close contact” for purposes of identifying individuals who may have been exposed to someone with Covid-19 and who should quarantine to avoid further transmission of the virus. Close contact is now defined as follows:
Someone who was within 6 feet 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.
*Individual exposures added together over a 24-hour period (e.g., three 5-minute exposures for a total of 15 minutes).
The CDC also clarified that the following factors should be considered when defining close contact:
- 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),
- Other environmental factors (crowding, adequacy of ventilation, whether exposure was indoors or outdoors).
Further, the determination of close contact should generally be made irrespective of whether the contact was wearing respiratory PPE. And, differential determination of close contact for those using fabric face coverings is not recommended.
Based on this new definition, when an employee tests positive for Covid-19, employers will have to undertake a broader investigation (likely with the assistance of public health authorities) to determine who has been in close contact with the infected individual.