Rochelle Walensky, director of Centers for Disease Control and Prevention (CDC), repeated findings from a flawed study to support her position on masking in schools on Tuesday.

During a Senate hearing, Walensky reiterated the need for masking in schools by claiming schools without mandates were more likely to risk outbreaks.

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Rochelle Walensky, Director of the U.S. Centers for Disease Control and Prevention (CDC), speaks during a Senate Health, Education, Labor, and Pensions Committee hearing in Washington, D.C., U.S., on Tuesday, Jan. 11, 2022. The hearing is titled "Addressing New Variants: A Federal Perspective on the COVID-19 Response." Photographer: Shawn Thew/EPA/Bloomberg via Getty Images (Photographer: Shawn Thew/EPA/Bloomberg via Getty Images)

"We have new science that has demonstrated the value of masking. 3.5 times increased risk of school outbreaks if you’re unmasked in schools vs. masking in schools," Walensky said.

This number referred to a study released by the CDC in September that claimed that schools in counties without mask mandates were 3.5 times more likely to experience a COVID-19 outbreak. This study has been heavily cited by Walensky in efforts to promote universal masking for children.

However, in December, this study came under fire by The Atlantic, who criticized several flaws within the methodology which, among other things, included 40 "virtual learning academies," roughly 20 preschools and roughly 90 "vocational programs associated with otherwise-listed schools."

The Center for Disease Control and Prevention (CDC) has been criticized and mocked from all sides after a series of muddled messages have baffled Americans amid a record surge in COVID-19 cases and the spread of the omicron variant. (iStock) (iStock)

"Still, the publication and agency endorsement of the Arizona study is especially demoralizing," Zweig wrote. "How did research with so many obvious flaws make its way through all the layers of internal technical review? And why was it promoted so aggressively by the agency’s director? I reached out to Walensky’s office to ask about the study, noting its evident limitations and outlier result. How, if at all, does this research figure into the agency’s continuing guidance for schools around the country? The CDC did not respond to my inquiries."

RAND PAUL RIPS FAUCI FOLLOWING LATEST HEARING FIREWORKS: HE DOESN’T WANT DEBATE BECAUSE HE ‘IS SCIENCE’ 

The CDC has also come under fire for shifting its recommendations regarding testing and quarantining. On Monday, a report suggested that the CDC would even recommend N95 or KN95 masks for protection against the omicron variant in defiance of previous allowances for cloth masks.

Corona virus prevention face mask protection N95 masks and medical surgical masks at home .

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The Senate hearing was also the setting for the latest heated exchange between Sen. Rand Paul, R-Ky., and Dr. Anthony Fauci over Facui's role with gain-of-function research.

Fox News’ Joseph Wulfsohn contributed to this report.