A new analysis of studies in the Centers for Disease Control and Prevention’s (CDC) flagship scientific journal found the agency promoted the effectiveness of masks using unreliable data with conclusions unsupported by evidence.
The preprint, published July 11 on MedRxiv, found the CDC’s Morbidity and Mortality Weekly Report (MMWR) made positive findings about the efficacy of masks 75 percent of the time, despite only 30 percent of studies testing masks, and less than 15 percent having “statistically significant results.”
No studies were randomized, yet the CDC in over half of their MMWR studies, made misleading statements indicating a causal relationship between mask-wearing and a decrease in COVID-19 cases or transmission, despite failing to show evidence of mask effectiveness.
The inappropriate use of causal language in MMWR studies was directly adopted by then CDC director Dr. Rochelle Walensky to promote masks and recommendations urging Americans to mask up. The authors said their findings “raise concern about the reliability of the journal for informing health policy” and suggest bias within the journal.
The MMWR, often called “the voice of the CDC,” is the agency’s primary vehicle for “scientific publication of timely, reliable, authoritative, accurate, objective, and useful public health information and recommendations.”
The publication—subject only to peer review internally by the agency—is frequently used to draft national health policies. For example, mask requirements implemented during the COVID-19 pandemic for federal workers, travelers, schools, businesses, healthcare workers, and Head Start programs—“mirrored” CDC recommendations.