The Centers for Disease Control and Prevention (CDC) expanded its definition of what it means to be a “close contact” of a person infected with COVID-19.
“Someone who was within six feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period” starting two days before symptom onset is now considered a close contact.
A new case report suggests that repeated short-term interactions with an infected person may be just as dangerous as single 15-minute exposures.
The Centers for Disease Control and Prevention (CDC) has expanded its definition of what it means to be a “close contact” of a person infected with the novel coronavirus.
Previous guidelines defined a close contact as someone who had spent at least 15 consecutive minutes within six feet of a person diagnosed with COVID-19. The CDC now considers a close contact as “someone who was within six feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period” starting from two days before illness onset or a positive test.
In other words, spending 15 minutes total—not just at one point in time—with an infected person over the course of a day is enough to qualify. For example, if you had one 10-minute exposure, one 3-minute exposure, and one 2-minute exposure, that would be a close contact.
Close contacts are supposed to quarantine for 14 days and maintain at least a six-foot distance from others following exposure, per the CDC. Understanding this new definition is crucial because even brief interactions are now believed to increase transmission risk, and will be included in contact tracing efforts.
The updated definition will “mostly impact workplaces, schools, and other places where people spend all day together off and on,” Caitlin Rivers, Ph.D., M.P.H., a senior scholar at the Johns Hopkins Bloomberg School of Public Health, told NPR. She explains that it has “the potential to significantly increase the number of people who are asked to quarantine.”
A case report published by the CDC this week spurred the new definition. The study recounts the case of a correctional facility employee in Vermont who contracted the virus after an estimated 22 exposures (less than a minute each) within six feet of a single incarcerated person with COVID-19. Despite only 17 total minutes of contact within an eight-hour shift, the employee caught the virus. Correctional officers wore a face mask and other PPE for their shifts, but incarcerated people were not required to wear face masks while inside their cells.
As schools, offices, and restaurants continue to reopen, this update will impact the way we think of the threat of transmission—and weigh the desire to return to “normal” against the necessity of safety. The COVID-19 pandemic is still relatively new, even at eight months in, and officials are still learning basic details about its transmission.
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