Abstract
Objective: To describe and evaluate the nature and methodology of reports and appropriateness of conclusions in MMWR pertaining to masks.
Background: Because Morbidity and Mortality Weekly Report (MMWR) has substantial influence on United States health policy, it is critical to understand the scientific process within the journal. Mask policies have been highly influenced by data published in the MMWR.
Methods: Retrospective cross-sectional study of MMWR publications pertaining to masks from 1978 to 2023. Outcomes included study design, whether the study was able to assess mask effectiveness, if results were statistically significant, if masks were concluded to be effective, if randomized evidence or conflicting data were mentioned or cited, and appropriateness of causal statements.
Results: 77 studies, all published after 2019, met our inclusion criteria. The most common study design was observational without comparator group 22/77 (28.6%). 0/77 were randomized. 23/77 (29.9%) assessed mask effectiveness. 11/77 (14.3%) were statistically significant, but 58/77 (75.3%) stated masks were effective. Of these, 41/58 (70.7%) used causal language. One mannequin study used causal language appropriately (1.3%). None cited randomized data. 1/77 (1.3%) cited conflicting evidence.