Important Study on Masking & Evidence: Does CDC Use Junk Science to Promulgate Mask Mandates?

A trio of well-respected University of California, San Francisco (UCSF)-affiliated medical researchers recently conducted a retrospective cross-sectional study of regular weekly reports generated by the Centers for Disease Control and Prevention (CDC) known as the MMWR publication with a focus on the subject of masks covering the time period of 1978 to 2023. This study’s main question concerns mask effectiveness. The importance of this investigation uploaded to the preprint server medRxiv should not be understated—the MMWR reports have substantial influence on American public health policy, if not beyond. While not peer reviewed, TrialSite has suggested in multiple analyses how MMWR output was exploited during the pandemic by political forces to effectuate various policies and agendas. Hence, the importance of a critical vetting of the scientific process associated with the CDCs output. The topic of concern with this latest piece concerns mask policies during COVID-19. Ultimately, 77 studies published since 2019 met the authors’ study design inclusion criteria, with 97.4% of these studies originating in the United States. Not surprisingly, observational studies without a comparator group 22/77 (28.6%) were most frequent. As was the case often with COVID-19 vaccine analysis in MMWR, community settings in this systematic analysis were most common (36/77; 45.5%). Not one randomized study was identified even though this category of study generates the strongest evidence. Of the analysis, 23/77 (29.9%) assessed mask effectiveness, with 11/77 (14.3%) being statistically significant, yet the great majority 58/77 (75.3%) stating masks as effective. Out of those, 41/58 (70.7%) used causal language. The authors found that just one mannequin study actually employed use of causal language in the appropriate manner (1.3%). 72/77 (93.5%) of the studies related to SARS-CoV-2 only, and none of these studies cited randomized data. Just one study (1/77 (1.3%) cited conflicting evidence. The bombshell finding: “MMWR publications pertaining to masks drew positive conclusions about mask effectiveness over 75% of the time despite only 30% testing masks and <15% having statistically significant results. No studies were randomized, yet over half drew conclusions were most often unsupported by the data. Our findings raise concern about the reliability of the journal for informing health policy.”

The study makes important points that cannot be ignored, let alone discounted. While the results are not yet peer reviewed, and generally evidence needs that validation (and this is no exception), TrialSite has monitored the CDC’s use of the MMWR during the pandemic and repeatedly reported on what appeared to be successful attempts at influencing various societally important decisions without the necessary evidence. Put another way, these CDC reports appear to serve as a justification for various decisions and policies, less the sufficient evidence justifying any particular decision or policy.