The stance by the Centers for Disease Control and Prevention (CDC) on face masks has taken many twists and turns throughout the COVID pandemic.

After initially claiming face coverings weren’t necessary, the CDC changed course in April 2020, calling on all Americans — even children as young as 2 years old — to mask up. 

That September, then-CDC Director Dr. Robert Redfield said during a Senate hearing that "face masks are the most important powerful health tool we have," even suggesting that they might offer more protection than vaccines.

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Those recommendations likely played a large part in 39 U.S. states eventually enacting mask mandates.

Now, a new scientific review suggests that widespread masking may have done little to nothing to curb the transmission of COVID-19

The review, titled "Physical interventions to interrupt or reduce the spread of respiratory viruses," was led by 12 researchers from esteemed universities around the world.

Dr. Rachelle Walensky, director of the Centers for Disease Control and Prevention, wears a mask. The CDC's stance on face masks has taken many twists and turns throughout the pandemic. (AP Photo/Susan Walsh, Pool, File)

Published by Cochrane Library, the review dug into the findings of 78 randomized controlled trials to determine whether "physical interventions" — including face masks and hand-washing — lessened the spread of respiratory viruses

A new scientific review suggests that widespread masking may have done little to nothing to curb the transmission of COVID.

When comparing the use of medical/surgical masks to wearing no masks, the review found that "wearing a mask may make little to no difference in how many people caught a flu-like illness/COVID-like illness (nine studies; 276,917 people); and probably makes little or no difference in how many people have flu/COVID confirmed by a laboratory test (six studies; 13,919 people)."

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Next, the review compared medical/surgical masks to N95 respirators (or P2 respirators, which are used in Europe).

It found that "wearing N95/P2 respirators probably makes little to no difference in how many people have confirmed flu (five studies; 8407 people); and may make little to no difference in how many people catch a flu-like illness (five studies; 8407 people), or respiratory illness (three studies; 7799 people)."

CDC

"It was the state and local authorities that took the CDC’s recommendations and implemented the mandates," Dr. Marc Siegel, a Fox News medical contributor based in New York City, told Fox News Digital. (iStock)

The 78 studies looked at participants from countries of all income levels. 

Data was gathered during the H1N1 flu pandemic in 2009, non-epidemic flu seasons, epidemic flu seasons up to 2016 and the COVID-19 pandemic, the study authors wrote.

Doctor says review had some key limitations

The new findings seem to call into question the CDC’s enthusiastic embrace of widespread masking.

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However, Dr. Marc Siegel, professor of medicine at NYU Langone Medical Center and a Fox News medical contributor, pointed out a key limitation: "The researchers focus primarily on randomized trials, but most of the studies that have been done on masks are population studies," he said. 

"There are very few randomized trials on masks."

"The recommendations may have been wrong, but the CDC doesn’t deserve the blame for everything."

— Dr. Marc Siegel

In a randomized trial, researchers place participants in different groups and observe the results in a controlled environment.

By contrast, population-based studies measure outcomes in a "real-world" setting.

Child wears mask in New York City school

In April 2020, the CDC called on all Americans — even very young children — to mask up against the coronavirus. (Reuters/Brendan McDermid/File Photo)

The study authors did admit to some limitations and a risk of bias, including the low number of people who followed mask guidance and the wide variation of outcomes. 

"The results might change when further evidence becomes available," they wrote.

‘Be sure of consistency’ 

Dr. Siegel said he has never supported mask mandates. 

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He believes that while masks might be effective on an individual level, they don’t work as well on a population level.

"If you’re going to mandate something, you’d have to be sure of consistency across the population, and that’s never happened," he said.

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However, the physician pointed out that the CDC never actually mandated masks — with the exception of a public transportation mandate in January 2021. 

Miami International Airport

As of right now, no U.S. states have mask mandates in place. (Getty Images)

"It was the state and local authorities that took the CDC’s recommendations and implemented the mandates," Dr. Siegel said. 

"The recommendations may have been wrong, but the CDC doesn’t deserve the blame for everything. I think they were aware that masks may have value on a personal basis, but they got carried away with the politics."

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As of right now, no U.S. states have mask mandates in place. 

On Sunday, New York dropped its state-wide mask requirement in hospitals — leaving the decision up to individual facilities. Many health care facilities are currently still requiring them.