FIRST ON FOX: Sen. Marsha Blackburn, R-Tenn., sent a letter to CDC Director Dr. Rochelle Walensky Wednesday suggesting the agency's new guidance encouraging K-12 schools to shut down some in-person extracurricular activities will harm the health of students.

In guidance updated Jan. 6, the CDC recommended that K-12 schools in areas with a "high" transmission rate of COVID-19 cancel "high-risk" extracurricular activities, which are defined as "those in which increased exhalation occurs, such as activities that involve singing, shouting, band or exercise, especially when conducted indoors."

Pointing out how the CDC classifies more than 99% of U.S. counties as experiencing high transmission rates, Blackburn said the CDC was effectively suggesting that nearly every county should be shutting down extracurricular activities.

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Describing the protocols as "misguided," Blackburn accused the Biden administration of "using the guise of COVID-19 to take away freedoms, seemingly without any regard for the well-being of our nation’s children," suggesting that banning activities like sports and band will further harm the mental health of young people.

She cited the CDC's own report, which found skyrocketing rates of suicide attempts among adolescents since the pandemic. A review of 36 other studies showed increases in anxiety, depression and other health issues.

Sen. Marsha Blackburn, R-Tenn.

Sen. Marsha Blackburn, R-Tenn., listens during the confirmation hearing for Supreme Court nominee Amy Coney Barrett before the Senate Judiciary Committee, Wednesday, Oct. 14, 2020, on Capitol Hill in Washington, D.C. (Stefani Reynolds/Pool via AP)

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"It is also difficult for Americans to trust that CDC guidance is based on scientific evidence, especially given the Biden administration’s propensity for – and the CDC’s prior history of — bowing to teachers’ unions," Blackburn added.

"Prior to the February 2021 CDC announcement on school-reopening guidelines, emails indicate that some CDC language in school reopening guidelines was actually written by the American Federation of Teachers (AFT)."

Rochelle Walensky

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., Jan. 11, 2022.  (Shawn Thew/EPA/Bloomberg via Getty Images)

Blackburn concluded by requesting that Walensky explain what evidence the CDC used to conclude that putting a halt to children playing sports will slow the spread of COVID-19 and cite any communication the agency has had with outside groups that might have influenced its guidance.

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"Our children’s health and well-being are on the line, and it is long past time for this administration to stop trying to micromanage the decisions Americans make about their own health," Blackburn said.

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