On October 21, 2020 the US Centers for Disease Control and Prevention (CDC) updated its definition of close contact. This term is used in multiple CDC COVID-19 guidance documents and guidelines to help the public respond to and manage the pandemic. In previous guidance, the CDC defined a close contact exposure as being within six feet of an infected person for 15 consecutive minutes or longer. Now a person should be considered to have had a close contact exposure if the person was within six feet of an infected individual for a cumulative total of 15 minutes or more over a 24-hour period. This new definition has the potential to increase the number of individuals who have had close contact with infected individuals and can also impact how the public deals with quarantining.
The CDC then lists a variety of factors that investigators should consider when determining whether a close contact occurred. These include the following:
- The duration of exposure
- Whether the individual has symptoms
- If the infected person was likely to generate respiratory aerosols (e.g. was coughing, singing shouting)
- Environmental factors such as crowding, adequacy of ventilation, and whether exposure was indoors or outdoors.
The CDC also recommends that the determination of close contact should generally be made irrespective of whether the contact was wearing respiratory PPE because the general public has not received training on proper selection and use of PPE.