https://www.medrxiv.org/content/10.1101/2023.07.07.23292338v1 Skip to main content medRxiv * Home * About * Submit * ALERTS / RSS Search for this keyword [ ] [Search] Advanced Search An analysis of studies pertaining to masks in Morbidity and Mortality Weekly Report: Characteristics and quality of all studies from 1978 to 2023 View ORCID ProfileTracy Beth Hoeg, View ORCID ProfileAlyson Haslam, View ORCID ProfileVinay Prasad doi: https://doi.org/10.1101/2023.07.07.23292338 Tracy Beth Hoeg 1University of California San Francisco, 550 16th St, 2nd Fl, San Francisco, CA 94158 2Department of Clinical Research, University of Southern Denmark, Odense, DK MD, PhD * Find this author on Google Scholar * Find this author on PubMed * Search for this author on this site * ORCID record for Tracy Beth Hoeg * For correspondence: tracy.hoeg@ucsf.edu Alyson Haslam 1University of California San Francisco, 550 16th St, 2nd Fl, San Francisco, CA 94158 PhD * Find this author on Google Scholar * Find this author on PubMed * Search for this author on this site * ORCID record for Alyson Haslam Vinay Prasad 1University of California San Francisco, 550 16th St, 2nd Fl, San Francisco, CA 94158 MD, MPH * Find this author on Google Scholar * Find this author on PubMed * Search for this author on this site * ORCID record for Vinay Prasad * Abstract * Full Text * Info/History * Metrics * Supplementary material * Data/Code * Preview PDF Loading Abstract Importance Because the MMWR has substantial influence on United States public health policy and is not externally peer-reviewed, it is critical to understand the scientific process within the journal. Mask policies during COVID is one topic that has been highly influenced by data published in the MMWR. Objective To describe and evaluate the nature and methodology of the reports and appropriateness of conclusions in MMWR pertaining to masks. Design, Setting and Participants Retrospective cross-sectional study of MMWR publications pertaining to masks from 1978 to 2023. Main outcome measures Study date, design, disease focus, setting, population and location. Whether the study was able to assess mask effectiveness, if results were statistically significant, if masks were concluded to be effective, if randomized evidence and/or conflicting data was mentioned or cited, if causal statements were made about effectiveness, and, if so, whether they were appropriate. Results 77 studies, all published after 2019, met our inclusion criteria. 75/77 (97.4%) studies were from the United States alone. All geographic regions and age groups were represented. The most common study design was observational without a comparator group 22/ 77 (28.6%). The most common setting was the community (35/77;45.5%). 0/77 were randomized studies. 23/77 (29.9%) assessed mask effectiveness, with 11/77 (14.3%) being statistically significant, but 58/77 (75.3%) stated masks were effective. Of these, 41/58 (70.7%) used causal language. Only one mannequin study used causal language appropriately (1.3%). 72/77 (93.5%) pertained to SARS-CoV-2 alone. None cited randomized data. 1/77 (1.3%) cited conflicting evidence. Conclusions and Relevance 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 causal conclusions. The level of evidence generated was low and the conclusions drawn were most often unsupported by the data. Our findings raise concern about the reliability of the journal for informing health policy. Competing Interest Statement Vinay Prasads Disclosures. (Research funding) Arnold Ventures (Royalties) Johns Hopkins Press, Medscape, and MedPage (Honoraria) Grand Rounds/lectures from universities, medical centers, non-profits, and professional societies. (Consulting) UnitedHealthcare and OptumRX. (Other) Plenary Session podcast has Patreon backers, YouTube, and Substack. Tracy Beth Hoegs Disclosures. (Honoraria) Brownstone Institute, Global Liberty Institute. (Consulting) Florida Department of Health (Other) Substack, payment for writing at The Atlantic, Los Angeles Times, New York Times, The Hill and Tablet Magazine. Dr. Haslam has no disclosures to report. Funding Statement This study did not receive any funding Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data produced are available online at https://github.com/ tracybethhoeg/mmwrmasks https://github.com/tracybethhoeg/mmwrmasks Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license. View the discussion thread. Back to top PreviousNext Posted July 11, 2023. Download PDF Supplementary Material Data/Code Email Thank you for your interest in spreading the word about medRxiv. NOTE: Your email address is requested solely to identify you as the sender of this article. Your Email * [ ] Your Name * [ ] Send To * [ ] [ ] [ ] [ ] [ ] Enter multiple addresses on separate lines or separate them with commas. 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[Send Message] Share An analysis of studies pertaining to masks in Morbidity and Mortality Weekly Report: Characteristics and quality of all studies from 1978 to 2023 Tracy Beth Hoeg, Alyson Haslam, Vinay Prasad medRxiv 2023.07.07.23292338; doi: https://doi.org/10.1101/ 2023.07.07.23292338 Share This Article: [https://www.medrxiv.org/content/10.1101/2023.07.07] Copy Reddit logo Twitter logo Facebook logo LinkedIn logo Mendeley logo Citation Tools An analysis of studies pertaining to masks in Morbidity and Mortality Weekly Report: Characteristics and quality of all studies from 1978 to 2023 Tracy Beth Hoeg, Alyson Haslam, Vinay Prasad medRxiv 2023.07.07.23292338; doi: https://doi.org/10.1101/ 2023.07.07.23292338 Citation Manager Formats * BibTeX * Bookends * EasyBib * EndNote (tagged) * EndNote 8 (xml) * Medlars * Mendeley * Papers * RefWorks Tagged * Ref Manager * RIS * Zotero * Tweet Widget * Facebook Like * Google Plus One Subject Area * Health Policy Subject Areas All Articles * Addiction Medicine (324) * Allergy and Immunology (632) * Anesthesia (168) * Cardiovascular Medicine (2398) * Dentistry and Oral Medicine (289) * Dermatology (207) * Emergency Medicine (381) * Endocrinology (including Diabetes Mellitus and Metabolic Disease) (850) * Epidemiology (11795) * Forensic Medicine (10) * Gastroenterology (705) * Genetic and Genomic Medicine (3766) * Geriatric Medicine (350) * Health Economics (637) * Health Informatics (2408) * Health Policy (939) * Health Systems and Quality Improvement (905) * Hematology (342) * HIV/AIDS (786) * Infectious Diseases (except HIV/AIDS) (13346) * Intensive Care and Critical Care Medicine (769) * Medical Education (368) * Medical Ethics (105) * Nephrology (401) * Neurology (3523) * Nursing (199) * Nutrition (528) * Obstetrics and Gynecology (679) * Occupational and Environmental Health (667) * Oncology (1832) * Ophthalmology (538) * Orthopedics (221) * Otolaryngology (287) * Pain Medicine (234) * Palliative Medicine (66) * Pathology (447) * Pediatrics (1037) * Pharmacology and Therapeutics (426) * Primary Care Research (424) * Psychiatry and Clinical Psychology (3187) * Public and Global Health (6178) * Radiology and Imaging (1290) * Rehabilitation Medicine and Physical Therapy (751) * Respiratory Medicine (832) * Rheumatology (380) * Sexual and Reproductive Health (373) * Sports Medicine (324) * Surgery (403) * Toxicology (50) * Transplantation (172) * Urology (147)