There’s no reset button on COVID-19 exposure.
That’s the concern underlying new changes to the Centers for Disease Control and Prevention’s definitions and guidance on social distancing during the pandemic, which will likely mean changes in some schools’ approach to preventing or tracing coronavirus outbreaks and significantly more students being identified for quarantine.
The CDC now defines a “close contact” of someone with COVID-19 as anyone who was within six feet of someone infected for a total of 15 minutes over the course of 24 hours. For example, if a student came into contact with a sick classmate three times during a school day, for five minutes each time, he would be asked to stay home and isolate himself for 14 days, while checking for fever, coughing, and other symptoms of COVID-19. Students and adults in schools would need to go into quarantine if they had close contact from two days before the infected person showed symptoms (or within two days of being tested, if the person had no symptoms) until the infected person started quarantine.
Previously, a close contact was someone who was close to an infected person for 15 minutes continuously, a rule that has led to confusion in schools about how best to limit exposure. For example, the Iowa Department of Public Health’s Medical Director Caitlin Pedati came out publically to discourage schools from using a so-called “COVID shuffle"—in which students are asked to get up and move around every 10-14 minutes to avoid students being close to one another for more than 15 minutes at a time.
This kind of social distancing can be counterproductive, because while 15 minutes is considered a rule of thumb, the risk of becoming infected goes up with any exposure, and some research has suggested asking students to move around frequently in an indoor, poorly ventilated classroom could actually increase their risk of exposure to the virus.
The CDC noted that students and teachers should still be considered “close contacts” even if they wear masks. While this wouldn’t change contact tracing and quarantine, separate research suggests that schools that use preventative strategies—universal mask wearing, six-foot social distancing, regular handwashing and cleaning—have significantly lower risk of infections.
A version of this news article first appeared in the Inside School Research blog.