On Wednesday, Walensky acknowledged that the CDC’s decision to alter the recommended isolation period “really had a lot to do with what we thought people would be able to tolerate.”
“We have seen relatively low rates of isolation for all of this pandemic. Some science has demonstrated less than a third of people are isolating when they need to,” Walensky told CNN.
“And so we really want to make sure that we had guidance in this moment — where we were going to have a lot of disease — that could be adhered to, that people were willing to adhere to and that spoke specifically to when people were maximally infectious,” she continued.
Indeed, the U.S. on Tuesday logged its highest single-day total of new Covid-19 cases, with 441,278 infections surpassing the previous daily record by close to 150,000. The dire state of the pandemic across the country demanded a change in CDC’s “conservative” guidance, Walensky said on Wednesday.
“In the context of the fact that we were going to have so many more cases — many of those would be asymptomatic or mildly symptomatic — people would feel well enough to be at work, they would not necessarily tolerate being home, and that they may not comply with being home, this was the moment that we needed to make that decision,” Walensky told CNN.
Last Thursday, the administration announced that health care workers who test positive for Covid-19 would be allowed to return to work after seven days, as opposed to the previously recommended 10 days, if they test negative and are asymptomatic after their isolation period.
Furthermore, the CDC advised that health care workers’ isolation period could be cut to five days, or even fewer, in the event of severe staffing shortages at U.S. hospitals.
Then, on Monday, the CDC announced that individuals who test positive for Covid-19 and are asymptomatic need to isolate for only five days, not 10 days, citing increasing evidence that people are most infectious in the initial days after developing symptoms.
The new CDC guidance, which is the same regardless of vaccination status, also recommends that individuals leaving isolation wear a mask for another five days following their self-quarantine.
“This was really a way to tell people: Make sure you isolate in those first five days, when you’re maximally infected,” Walensky told NBC on Wednesday.
Still, the new CDC guidance does not require individuals at the end of their isolation period to test negative for Covid-19 before reentering society — a point of contention for some public health experts who have criticized the agency‘s revised recommendation.
“It’s frankly reckless to proceed like this,” Eric Topol, founder and director of the Scripps Research Translational Institute, told The Associated Press on Tuesday. “Using a rapid test or some type of test to validate that the person isn’t infectious is vital.”
But Walensky on Wednesday said the CDC decided against requiring a negative test result as part of its new guidance because the agency is still unaware of how well Covid-19 rapid antigen tests “predict whether you’re transmissible during the end of disease.”
“If you got a rapid test at five days and it was negative — we weren’t convinced that you weren’t still transmissible — we didn’t want to leave a false sense of security. We still wanted you to wear the mask,” Walensky told CNN.
“And if it was positive — we still know the maximum amount of transmission was behind you — we still wanted you to wear a mask,” she added. “And given that we were not going to change our recommendations based on the result of that rapid test, we opted not to include it.”
As for the more accurate Covid-19 PCR tests — which use real-time polymerase chain reaction technology and generally take hours to produce results — Walensky said they were not included in the new CDC guidance because they can show positive results up to 12 weeks after initial infection.
“That is not going to be helpful,” Walensky told NBC. “You’re not going to be transmitting during all of that period of time.”
Although Walensky defended the CDC’s decision not to add a negative testing requirement to its new guidance, she still promoted the overall efficacy of antigen tests — which the FDA on Tuesday warned might be less capable of detecting the Omicron variant.
“We do know that the antigen test may not perform as well as it had for prior variants — the Alpha variant and the Delta variant — but it’s still picking up quite a bit of infection,” Walensky said.
Walensky went on to reiterate the CDC’s guidance that if an individual receives a negative result from an antigen test but experiences Covid-19 symptoms, they “should go ahead and get that PCR test” to better diagnose a potential infection.
Pressed on why the CDC’s guidance last Thursday for health care workers included a negative-testing requirement while its guidance on Monday for all Americans did not, Walensky told CNN that “infection control recommendations in the health care workplace are always more stringent for health care workers than they are for the general population.”
Walensky also denied that the absence of a negative-testing requirement in the CDC’s new guidance was related to a shortage of tests, telling CBS: “This really had nothing to do with supply.”
President Joe Biden pledged in a White House address on Dec. 21 that his administration would buy 500 million at-home rapid antigen tests that Americans will be able to order for free beginning in January.
But details about the purchasing plan remain murky, and Arkansas Gov. Asa Hutchinson, chair of the National Governors Association, has warned it could interfere with state-level efforts already underway to boost testing supply.