After questioning the standard of common mask-wearing at the start of the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) decided that the practice was so effective that it should be legally mandated even for 2-year-olds. A new review of the evidence suggests the CDC got it right the first time.
This review, published by the Cochrane Library, an authoritative collection of scientific databases, analyzed 18 randomized controlled trials (RCTs) that aimed to measure the effect of surgical masks or N95 respirators on respiratory viral infections. It found that wearing masks in public places “probably makes little or no difference” to the number of infections.
These findings go to the heart of the case for the mask mandate, a policy that generated much resentment and anger during the pandemic. They also show that the CDC, which has repeatedly exaggerated the evidence in favor of masks, cannot be trusted as a source of public health information.
In September 2020, then-CDC Director Robert Redfield described masks as “the most important, powerful public health tool we have.” He claims that masks offer more protection against COVID-19 than vaccines.
“The evidence is clear,” Redfield’s successor, Rochelle Walensky, insisted in November 2021, when she “denied a reduction” in wearing a mask.[es] Your chance of infection is greater than 80 percent.” Three months later, the CDC claimed that it published a study showing that “wearing a mask reduces the chance of a positive test by 83 percent”.
These statements were based on two sources of evidence with widely recognized flaws: laboratory tests under stylized conditions and observational studies that do not fully account for variables that influence virus transmission. RCTs are designed to avoid these problems by comparing disease rates among subjects randomly assigned to wear masks under real-life conditions with disease rates in control groups.
If masks have the dramatic effect that the CDC claims, you’ll see evidence of this in RCTs. But the Cochrane review found no association between mask wearing and disease rates, whether measured by reported symptoms or laboratory tests.
When it comes to symptoms consistent with COVID-19 or influenza, the authors report, “wearing a mask in the community probably makes little or no difference.” They reached the same conclusion in laboratory-confirmed cases.
Two RCTs were conducted during the pandemic, one in Denmark and one in Bangladesh. The first found no protective effect, while the second found that symptoms consistent with COVID-19 were about 11 percent less common in the masked group.
The latter result was much less impressive than the results of the observational study that the CDC said in February 2022. In that study, the CDC reported, surgical masks like those used in the Bangladesh RCT reduced the risk of infection by 66 percent. Even cloth masks, which the CDC admits are the least effective type, supposedly reduced infections by 56 percent.
This gloss obscures serious methodological problems with CDC-promoted studies, including sampling bias, recall bias, and failure to consider “other preventive behaviors.” As the Cochrane review notes, the Bangladesh study also suffered from several weaknesses, including “baseline imbalance, subjective outcome assessment and incomplete follow-up across groups.”
In any case, including the Bangladesh RCT, which accounted for a large portion of the data in the Cochrane meta-analysis, did not change the overall results, indicating “little or no effect of mask use”. And contrary to expectations that N95 respirators would prove superior to surgical masks, the review found that existing evidence “demonstrates no difference in clinical effectiveness.”
The authors suggested several possible explanations for these findings, including “poor study design”, inconsistent or inappropriate mask use, “self-contamination of the mask by hands”, “saturation of the mask with saliva”, and risk based on “a” Taken increases an exaggerated sense of security.” But one thing is clear: Instead of following the science on the mask, the CDC has distorted it to support a preconceived conclusion.
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