FILE - Student wearing mask

(The Center Square) – The U.S. Centers for Disease Control and Prevention changed course Tuesday, reversing its previous COVID-19 guidance by urging Americans to wear masks, regardless of their vaccination status. Critics quickly denounced the reversal, saying it undermines vaccine confidence.

The CDC said all students and teachers should wear masks, even if they are vaccinated, and that all Americans, including those with the vaccine, should wear masks in public places where the virus has a significant presence. The agency cited the delta variant of COVID, which is more transmissible.

The CDC had previously announced in May that vaccinated individuals did not have to wear masks. The White House fended off questions from reporters at the White House press briefing on the reasoning behind that reversal.

"When [Biden] made those comments back in May, we were dealing with a very different strain of the virus than we are today," Psaki told reporters. "And delta is more transmissible. It is spreading much more quickly."

The decision throws more fuel on the fire as Americans debate the efficacy and safety of the vaccine and many have already expressed their disapproval of the new mandates. The CDC’s announcement took fire from Republicans, who argue it will further weaken Americans’ confidence in the vaccine.

“The CDC’s updated guidance deeply undermines vaccine confidence. Mask mandates for more command and control will not build trust – only resentment,” House Energy and Commerce Republican Leader Cathy McMorris Rodgers said. “The Biden Administration should be leading with science, not shame and fear.”

The Biden administration also has grappled with whether to require vaccinations.

The Department of Veterans Affairs Secretary Denis McDonough announced Monday that health care personnel working for the agency must get the COVID vaccine. The rule includes “physicians, dentists, podiatrists, optometrists, registered nurses, physician assistants, expanded-function dental auxiliaries and chiropractors,” all of whom have eight weeks to get the vaccination.

“We’re mandating vaccines for Title 38 employees because it’s the best way to keep Veterans safe, especially as the Delta variant spreads across the country,” McDonough said. “Whenever a Veteran or VA employee sets foot in a VA facility, they deserve to know that we have done everything in our power to protect them from COVID-19. With this mandate, we can once again make – and keep – that fundamental promise.”

Even before news broke about the CDC’s reversal, some state and local governments already had begun putting in place their own requirements.

California’s Democratic Gov. Gavin Newsom announced Monday that all health care workers and state employees must show proof of vaccination or undergo weekly COVID tests.

Los Angeles County took similar measures, requiring residents to wear masks while indoors “regardless of vaccination status.”

"We share our deepest condolences with those of you who have lost friends, loved ones, and family during this difficult time,” Los Angeles County Health Officer Muntu Davis said in the announcement. “We expect to keep masking requirements in place until we begin to see improvements in our community transmission of COVID-19. But waiting for us to be at high community transmission level before making a change would be too late.”

New Orleans, St. Louis and Chicago have put mask mandates in place as well, among others.

The mandates have become a major point of controversy. St. Louis' indoor mask mandate has been challenged with a lawsuit by the state’s attorney general.

"This continued government overreach is unacceptable and unconstitutional, especially in the face of a widely available vaccine. There is absolutely no scientific reason to continue to force children to wear a mask in school,” the state’s Republican Attorney General, Eric Schmitt, said. Schmitt also is running for Senate. “Back in May, I filed suit against St. Louis County for continuing to impose such unlawful restrictions, and just three days later, those restrictions were lifted. I will continue to fight this seemingly unending control and intrusion on peoples’ lives – we will not back down.”

D.C. Bureau Reporter

Casey Harper is a Senior Reporter for the Washington, D.C. Bureau. He previously worked for The Daily Caller, The Hill, and Sinclair Broadcast Group. A graduate of Hillsdale College, Casey's work has also appeared in Fox News, Fox Business, and USA Today.