The Centers for Disease Control and Prevention is facing criticism over the messaging surrounding its updated coronavirus guidelines and statements that appear contradictory as the nation faces a shortage of coronavirus tests.

CDC Director Rochelle Walensky said this week that her agency did not initially include a testing component in its revised 5-day quarantine guidelines because of testing unreliability while arguing that PCR tests can be positive for up to 12 weeks and rapid tests are not FDA-approved to gauge transmissibility. 

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CDC Director Dr. Rochelle Walensky (REUTERS/Kevin Lamarque)

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However, the CDC recently embraced the "test to stay" plan for schools allowing unvaccinated students exposed to the virus to stay in school if they tested negative twice in the week after exposure.

On Wednesday, Walensky was questioned by a reporter as to why the CDC issued a guideline saying healthcare workers could return to work after seven days with a negative test only to issue another guideline days later, not requiring a negative test after five days to return to work. 

The reporter suggested that the change was due to the shortage of tests in the United States, to which Walensky replied, "First of all, this has nothing to do with the shortage of available tests, because you can see in our quarantine guidance that we actually do recommend a test for people to emerge from quarantine."

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical adviser to the president ((AP Photo/Andrew Harnik))

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The new guidance, which some believe was in response to backlash from medical experts over halving quarantine requirements, suggests that people get tested "if an individual has access to a test and wants to test."

After the CDC revised the guidelines to include a testing component amid a national test shortage crisis, the White House dismissed concerns that pushback from the public, and not science, were dictating coronavirus recommendations from the government. 

"The CDC is absolutely led by data and science," White House Press Secretary Jen Psaki said Wednesday. "And, you know, again, if they hadn't changed their recommendations over the course of time, schools would probably be closed across the country…here's the difference from the last administration. We are not driving our decision-making on how we're addressing the pandemic through messaging or through political concerns." 

White House chief medical adviser and director of the National Institute of Allergy and Infectious Disease, Dr. Anthony Fauci, had specifically mentioned "pushback" in relation to COVID policy just days earlier.

In a Time interview published on Wednesday, Walensky said that the revised guidance considered several factors beyond science including keeping the labor force operational. 

"There are a lot of studies [from other variants] that show the maximum transmissibility is in those first five days. And [with omicron] we are about to face hundreds of thousands more cases a day, and it was becoming very, very clear from the health care system that we would have people who were [positive but] asymptomatic and not able to work, and that was a harbinger of what was going to come in all other essential functions of society."

Last week, Walensky admitted that her CDC guidelines were partially based on what she "thought people would be able to tolerate."

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Walensky’s CDC has been widely criticized and mocked from both sides of the aisle over its recent messaging amid a record surge in COVID-19 cases and the spread of the omicron variant.

"Honestly, right now the CDC’s slogan should just be, ‘We have no idea,’" Jimmy Fallon joked on Tuesday night during his "Tonight Show" monologue. "Seriously, at this point, you’re better off waiting a month to hear what the groundhog has to say."

The CDC updated its guidance around isolation again on Tuesday, declining to add a clear testing recommendation while saying that people can take a test if they have "access" and "want to." The new guidelines came as millions of Americans wait in hours-long lines to get tested during a record-breaking surge in cases. 

The agency halved its recommended isolation and quarantine time last week, saying that a person infected with COVID-19 can leave isolation after five days if they're asymptomatic, followed by five days of wearing a mask. Medical experts pushed back on that recommendation, saying that it may result in people leaving isolation while they're still infectious. Dr. Fauci initially responded to the criticism by claiming on Sunday that a testing recommendation may be added, but the CDC ultimately declined to add it to the updated guidance. 

A sign was posted at the front of this CVS pharmacy at the Capitol in Jackson, Miss., Monday, Jan. 3, 2022. It was widely reported that the at-home COVID-19 tests were in very short supply throughout the state. (AP Photo/Rogelio V. Solis) 

"Pod Save America," a liberal political podcast hosted by former Obama White House staffers, invited University of California San Francisco Department of Medicine chair Dr. Bob Wachter on the program to slam the CDC. 

"The thing that really bugged me was, I think they should have just told the truth. You know, ‘We have a limited number of tests and if you can’t get a test, and you feel perfectly fine, we think the risk of you going out into civilization is quite low, you should wear a really good mask for the next five days and be super careful around vulnerable people,’" Wachter said. "That would have been OK. The message they put out was the tests don’t work very well on day five. That’s just wrong." 

The CDC did not immediately respond to a request for comment from Fox News. 

Fox News’ Brian Flood contributed to this report