The new duration comes with some asterisks: Namely, the five-day rule should apply only to those no longer feeling symptoms or running a fever. And even once isolation ends, infected people should spend the following five days wearing a mask when around others. The agency also amended its recommendations for those exposed to COVID. Previously, fully vaccinated people didn’t need to quarantine after an exposure. Now, only those who have received a booster shot can skip quarantine, so long as they wear a mask in all settings for 10 days.

The Omicron variant is spreading at unprecedented rate, shattering previous one-day records. Per the New York Times’ tracker, the U.S. has seen a 153% two-week increase in positive tests; the country currently has the most known COVID cases of any nation on earth. 

The news sparked a fair amount of derision on social media, as many health professionals zeroed in on the same weak point in the new rule: The CDC did not specify a negative antigen test as a requirement for leaving isolation.

On Monday, Dr. Michael Mina, a physician and former professor at Harvard’s Center for Communicable Disease Dynamics, called the CDC’s decision “reckless” because it did not take into account a negative test. 

“I am 100 percent for getting people to drop isolation early,” Mina said in a tweet. “Heck, I formally recommended it to the CDC in May 2020 and published the recommendation in [the Journal of Clinical Infectious Diseases] in April 2020. But it was always with a negative test. What the heck are we doing here?”

Former Surgeon General Jerome Adams advised against following the guidance, saying people should get a negative test before leaving isolation. 

“I love the CDC. Grew up wanting to work there and have been one of their most ardent defenders. I never dreamed the day would come when I would advise people NOT to follow their guidance,” Adams tweeted on Tuesday. “They wouldn’t even follow it for their own family.”

Dr. Adams followed up by calling the change “a compromise to keep the economy open in the face of inadequate tests.”

For its part, the CDC said the guidelines were updated to reflect recent evidence suggesting COVID-19 transmission most often occurs one to two days before the onset of symptoms and two to three days after. 

“With the sheer volume of new cases that we are having and that we expect to continue with Omicron, one of the things we want to be careful of is that we don’t have so many people out,” Dr. Anthony Fauci, the Biden administration’s chief medical adviser, told CNN’s Jim Acosta. “I mean, obviously if you have symptoms you should [stay home], but if you’re asymptomatic and you’re infected, we want to get people back to jobs—particularly those with essential jobs to keep our society running smoothly.”

Essential jobs include those in hospital and health care settings. After many hospitals reported staff shortages—stemming from both record resignations and staff out sick—the CDC amended its quarantine rules for health care workers specifically.  

“Health care workers with COVID-19 who are asymptomatic can return to work after seven days with a negative test, and that isolation time can be cut further if there are staffing shortages,” the agency wrote last week. “Health care workers who have received all recommended COVID-19 vaccine doses, including a booster, do not need to quarantine at home following high-risk exposures.”

On CNN, Fauci said he supported the CDC’s decision, calling it “very prudent and good.”

“Now that we have such an overwhelming volume of cases coming in, many of which are without symptoms, there’s the danger that this is going to have a really negative impact on our ability to really get society to function properly,” Fauci said in an interview on NewsNation.  “The CDC made a decision to balance what’s good for public health [with] keeping the society running.”

Many on social media mocked the loosened regulations, which they viewed as a hollow effort by the CDC to keep people at work, rather than keep people safe. Some others made jokes about the perceived randomness and inconsistency of the center’s messaging.