Time to Revisit Your Contact Tracing Protocols after CDC Redefines Close Contact as 15-Minutes of Cumulative Exposure

Contributed by Michael J. Faley, October 22, 2020

15 Minutes Clock Icon. Vector Fifteen Minute Symbol Isolated on White Background.

The US Centers for Disease Control and Prevention (CDC) has revised its guidelines to define a close contact with a COVID-19 carrier to include several brief exposures. The CDC now defines “close contact” with an infected person as “[s]omeone 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.”  The change now means that the 15-minutes of exposure time includes shorter interactions added together over a 24-hour period, including, for example, three 5-minute exposures for a total of 15 minutes.

The CDC readily acknowledges that it is difficult to precisely define what really constitutes “close contact,” but advises that 15 cumulative minutes of exposure at a distance of 6 feet or less can be used as an operational definition for contact investigation. Factors to think about when deciding whether close contact has occurred include: 

  • The proximity of the individuals (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).

The CDC further advises that “[b]ecause the general public has not received training on proper selection and use of respiratory PPE, such as an N95, the determination of close contact should generally be made irrespective of whether the contact was wearing respiratory PPE.  At this time, differential determination of close contact for those using fabric face coverings is not recommended.”

The new guidelines seemingly add another layer of complexity to the contact tracing process. Nonetheless, employers should take a look at their COVID-19 policies and contact tracing protocols and incorporate the CDC’s revised definition of close contact. Employers should also be sure to check their local and state guidance.