CDC’s Own Scientists Found Masks Ineffective for COVID, but Agency Recommended them Anyway – Michael Nevradakis, Ph.D. 2/9/24


The Centers for Disease Control and Prevention’s (CDC) own scientists conducted studies showing N95 respirators are no more effective at stopping viruses than surgical masks — yet the agency issued guidance contradicting those and other studies showing both types of masks are ineffective at stopping the spread of COVID-19, according to an investigation by independent journalist Paul D. Thacker.

The investigation, published this week in two parts on The Disinformation Chronicle, details how CDC leadership openly questioned the findings of CDC scientists’ studies contradicting the agency’s public messaging about mask effectiveness.

During the pandemic, mask advocates “shifted goalposts and demanded N95 respirators,” Thacker said, claiming they perform better than surgical masks at stopping the virus.

However, Thacker said CDC scientists found no difference between N95 and surgical masks in the ability to stop the spread of respiratory viruses. The findings of the CDC studies are consistent with other peer-reviewed studies on the efficacy of masks in preventing COVID-19, according to Thacker.

“But the CDC responded by saying people can’t say that,” Thacker told The Defender.

To shut down the controversy, the CDC, in its Jan. 23 post on preventing the transmission of pathogens in healthcare settings, warned researchers that to suggest facemasks and respirators are the same “is not scientifically correct,” Thacker wrote.

CDC ignores own studies questioning N95, mask effectiveness

According to Thacker, CDC guidance for controlling the spread of infections had not been updated since 2007. This prompted the CDC, in 2022, to select “a bunch of science experts,” and ask them “to update the agency’s scientific guidance to hospitals on how to control infections.”

In November 2023, the experts produced an 80-page systematic review and meta-analysis, examining whether N95 respirators were more effective than surgical masks. The review found that while N95 respirators are better at filtering particles, the finding that they are more effective at stopping viruses “has been less conclusive.”

The systematic review also examined the “effectiveness” of N95 respirators and surgical masks “under ‘real world’” conditions and found “no difference” between the two.

The review also found numerous symptoms reported by N95 mask users, including: “difficulty breathing, headaches, and dizziness; skin barrier damage and itching; fatigue; and difficulty talking.”

According to Thacker, the CDC is not pleased with these findings, suggesting in its recent update that its own scientists were wrong.

“Although masks can provide some level of filtration, the level of filtration is not comparable to NIOSH Approved respirators,” the CDC said.

The post also stated, “The COVID-19 pandemic has forever changed the approach we take in healthcare settings to protect healthcare personnel, patients, and others from transmission of respiratory infections.”

More evidence contradicting the CDC’s public position came at a June 2023 CDC meeting in Atlanta, when Erin Stone, MPH, a public health analyst in the agency’s Office of Guidelines and Evidence Review, presented the findings of a meta-analysis on the effectiveness of N95 respirators and surgical masks.

According to Stone, the data “suggests no difference” in their effectiveness.

Yet, in November 2023 testimony before the U.S. House of Representatives’ Energy and Commerce Committee, CDC Director Mandy Cohen sidestepped questions regarding mask effectiveness and refused to deny she would reinstate mask mandates for children.

According to Thacker, in December 2023, just six days after Cohen’s testimony, The BMJ’s Archives of Disease in Childhood journal published a study finding that “mask recommendations for children are not supported by scientific evidence.”

“Recommending child masking does not meet the accepted practice of promulgating only medical interventions where benefits clearly outweigh harms,” the study authors noted.

Thacker: CDC guidance based on politics, not science

Thacker said the CDC contradicted its own findings on mask efficacy even in the early stages of the COVID-19 pandemic.

“Soon after the pandemic started, the CDC began promoting masks to stop the spread of COVID,” Thacker wrote. “And it did so despite CDC publishing a May 2020 policy study in their own journal, ‘Emerging Infectious Diseases,’ that did not find a ‘substantial effect’ for masks in stopping the transmission of respiratory viruses.”

#WearAMask 😷 in public to help #SlowTheSpread of #COVID19. When choosing a mask, make sure it fits snugly against your face, covers your nose and mouth, and has multiple layers. More on masks:

— CDC (@CDCgov) April 3, 2021

That same month, the CDC began publicly promoting N95 respirators as a more effective means of controlling the spread of COVID-19.

However, on its webpage promoting the superiority of N95 respirators, the CDC admitted “there’s not a whole lot of evidence that N95 respirators do in fact work better than masks at stopping viruses,” Thacker wrote.

“Laboratory studies have demonstrated that FFRs [filtering facepiece respirators] provide greater protection against aerosols compared with surgical masks … however, the results of clinical studies have been inconclusive,” the CDC wrote, citing a 2019 study in JAMA comparing N95 respirators to masks.

“Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza,” the JAMA study noted.

Given the shortage of N95 respirators during this global outbreak of #COVID19, it’s important to understand the difference between N95 respirators and surgical masks, and how both are intended to protect healthcare workers. Learn more from @NIOSH:

— CDC (@CDCgov) May 2, 2020

According to Thacker, the results of these studies confirm the widely accepted pre-COVID-19 scientific consensus on the ineffectiveness of masks of any kind in stopping the spread of viruses. Thacker cited statements the World Health Organization made in 2019 and the CDC’s guidance on virus control.

In a 2020 appearance on CBS’ “60 Minutes,” Dr. Anthony Fauci said that while a mask might “block a droplet” and “make people feel a little better,” it does not provide “the perfect protection that people think it is.”

According to Thacker, “For some reason, a ‘masks work’ political movement began to grow,” despite Fauci’s statements and the findings of these studies.

“I’m not really sure what happened or what we do next,” Thacker wrote. “But something weird took place in America where liberal elites began messaging among themselves ‘masks work.’ They then grew this into a crusade.”

The movement was effective in getting the CDC on board with issuing mask guidance, Thacker said.

Four years after the onset of the pandemic, the CDC now openly cheerleads for masks, despite research the agency published showing that masks don’t really protect people from catching viruses, he said.

“And this is why the experts advising the CDC are getting all this pushback: they didn’t tell the CDC what the CDC wanted to hear,” Thacker wrote.

Harvey Risch, M.D., Ph.D., professor emeritus and senior research scientist in epidemiology (chronic diseases) at the Yale School of Public Health, told The Disinformation Chronicle the CDC “has succumbed to political influences.”

Risch said:

“It made policies for school closures in order to please the teachers’ union. Its charitable organization allows pharma to feed it hundreds of millions of dollars that would be illegal to go directly to the agency, and this gives pharma major influence on CDC policies.”

According to Thacker, the CDC has continued to double down on guidance promoting mask efficacy. A Jan. 23 letter the agency sent to its own advisers appears to encourage them to add more mask guidance to the agency’s new guidelines for the spread of pathogens, based on the conclusion that N95 respirators are effective.

“Too much science is forcing CDC to request a science do over,” Thacker wrote, referring to the CDC’s Jan. 23 post, which states that its new recommendations should not “be misread to suggest equivalency between facemasks and NIOSH Approved respirators, which is not scientifically correct nor the intent of the draft language.”

Thacker said his investigation shows that “in their guidance to the CDC, experts do recommend masks as part of what they call ‘transmission-based guidance’ which the CDC defines as a second tier of infection control.” However, the CDC’s own guidance also finds that masks are effective only for “source control” — preventing an already infected person from infecting others.

“But this isn’t what the CDC wants,” Thacker wrote. “They want the experts to write guidelines that recommend healthy people wear masks, even though research shows masks won’t really stop healthy people from getting sick.”

“The CDC has caught the ‘masks work’ political wave and is now demanding that independent experts conform to their preferred mask dictates,” he added.

In doing so, the CDC is rejecting science it doesn’t like, including several other non-CDC studies that have questioned mask effectiveness.

A study published in Annals of Internal Medicine in November 2022 found no difference between N95 respirators and surgical masks in stopping the spread of COVID-19. These findings were mirrored in a January 2023 Cochrane meta-analysis on mask effectiveness.

According to the Cochrane report, “The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the objective and more precise outcome of laboratory‐confirmed influenza infection.”

A May 2023 study published in Ecotoxicology and Environmental Safety suggests N95 respirators may expose wearers to dangerous levels of toxic compounds linked to seizures and cancer.

A September 2023 meta-analysis published in Clinical Research Study examined mask studies published since 2019 in the CDC’s Morbidity and Mortality Weekly Report (MMWR).

According to the findings of the meta-analysis:

“MMWR publications pertaining to masks drew positive conclusions about mask effectiveness >75% of the time despite only 30% testing masks and <15% having statistically significant results. No studies were randomized, yet over half drew causal conclusions.

“The level of evidence generated was low and the conclusions were most often unsupported by the data. Our findings raise concern about the reliability of the journal for informing health policy.”

Real-world examples also call into question narratives regarding mask efficacy.

Sweden, for instance, did not mandate or recommend masks for the general public during the first wave of the COVID-19 pandemic, and only did so in certain situations in the later stages of the pandemic, according to The Conversation. Yet, its total excess deaths during the first two years of the pandemic were among the lowest in Europe.”

In 2020, Swedish state epidemiologist Anders Tegnell said, “We see no point in wearing a face mask in Sweden, not even on public transport,” adding there were “at least three heavyweight reports … which all state that the scientific evidence is weak.”

A Swedish government commission noted low levels of excess mortality in 2020 and 2021 and said that, at most, masks should have been “recommended.”

Soon after the report was released, a Feb. 25, 2022, Boston Herald op-ed stated that Sweden “got it right.”

“I don’t understand what is driving the ‘masks work’ political movement,” Thacker told The Defender. “There were plenty of stories written pointing out that there isn’t much scientific evidence that masks stop respiratory virus spread.”

“Maybe people were just scared and wanted to believe masks provide protection?” he said.

Thacker also cited the historical precedent of the Spanish Flu epidemic in 1918, when the Red Cross campaigned for masks all across America.

“California’s state board of health ran a study comparing towns that had mask mandates against those that did not. They found that there was no difference and published the study in the American Journal of Public Health in 1920,” Thacker said.

“Maybe these mask campaigners need to read a little history,” he added.

Thacker is now calling on whistleblowers inside the CDC to contact him “to discuss what is going on inside the agency.”

“I’m talking to CDC people and hope to learn what is going on inside the agency. I plan to write more on this,” Thacker told The Defender.

“CDC Director Mandy Cohen wants to restore trust in the agency, but that won’t happen if she keeps putting politics ahead of scientific evidence,” he said.