The director of the Centers for Disease Control and Prevention is defending new COVID-19 isolation guidelines after criticism that a negative test result recommendation should have been included. 

CDC Director Rochelle Walensky appeared on several morning shows on Wednesday to explain why the agency earlier this week reduced the recommended isolation time for people who test positive for COVID-19 from 10 days to five days if they’re asymptomatic. Some experts criticized the guidelines, arguing the CDC should recommend a negative test result prior to leaving isolation. 

Walensky addressed this criticism on CNN, saying the agency decided not to recommend a rapid test to leave isolation because “we actually don’t know” how well rapid tests “predict whether you’re transmissible during the end of disease.” She added that regardless of whether a rapid test at the end of isolation is negative or positive, the CDC’s recommendation either way would be to wear a mask, so “given that we were not going to change our recommendations based on the result of that rapid test, we opted not to include it.” 

The new guidelines were made based on the fact that “about 85 to 90 percent of viral transmission happens in those first five days,” and “we want to be able to get people back out if they’re feeling well,” Walensky told CBS This Morning, adding the decision had “nothing to do with” rapid tests not being more widely available. The CDC is still recommending that those exposed to COVID-19 get tested on day five “if possible.” 

On CNN, Walensky also said the CDC took into account “what we thought people would be able to tolerate,” noting “we have seen relatively low rates of isolation” during the pandemic and that the agency wanted to ensure it had guidelines in place that “people were willing to adhere to.”