On October 21, the Centers for Disease Control and Prevention (CDC) changed the definition of what is meant by a “close contact” with someone with COVID-19 after a study suggested COVID-19 can be passed in shorter interactions than previously thought.
The CDC previously defined a close contact as someone who has been within 6 feet of an infected person for 15 minutes or more continuously. The description has now expanded to someone who has spent a cumulative total of 15 minutes or more within 6 feet of an infected person over a 24-hour period, even if the time isn't consecutive. That period starts two days before illness onset (or, for asymptomatic patients, two days prior to test specimen collection) until the time the patient is isolated. The "15 minutes" can now defined as individual exposures added together over a 24-hour period (such as, three 5-minute exposures for a total of 15 minutes).
The CDC goes on to write: "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).”
While these factors do not mitigate the determination of whether a person is deemed a close contact, they may provide reassurance regarding individual risk of exposure. Also, the CDC states that the use of face coverings is not a factor in determining whether a person is a close contact.
Read more about the new definition here.