WASHINGTON — On Tuesday, March 1, 2022, Sen. Ron Johnson (R-Wis.), ranking member of the Permanent Subcommittee on Investigations, sent a letter to the Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky seeking answers on her repeated reliance on a potentially flawed study of the effectiveness of mask mandates in schools. Recent reporting identified serious flaws in study’s findings and methodology.
The senator wrote, “Between September and October 2021, you publicly cited the study multiple times to support the conclusion that mask mandates in schools help prevent COVID-19 infections.”
Months later in private, the senator noted that, Director Walensky acknowledged the “limitations” of the study.
Because of the apparent inconsistencies with CDC’s statements about this study, the senator requested all documents and communications relating to the study. The senator also requested the CDC clarify potential false statements to subcommittee staff.
Read more about the letter in Fox News.
The full text of the letter can be found here and below:
March 1, 2022
Rochelle Walensky, MD, MPH
Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30329
Dear Director Walensky:
On September 21, 2021, the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR) published a study titled, “Association between K-12 School Mask Policies and School-Associated COVD-19 Outbreak – Maricopa and Pima Counties, Arizona, July-August 2021” (hereinafter “the study”). Between September and October 2021, you publicly cited the study multiple times to support the conclusion that mask mandates in schools help prevent COVID-19 infections. On December 16, 2021, The Atlantic, published an article that highlighted several purported flaws in the study. I write to request information related to CDC’s evaluation, publication, and use of a potentially flawed study in support of school mask guidance.
Beginning in September 2021, you began to cite the study as evidence in support of CDC’s guidance that advocated for mask mandates in schools. On September 26, 2021, during an interview on CBS Face the Nation, you stated, “[CDC] also published a study out of Arizona that demonstrated that places that had no masks in place were three and half times more likely to have outbreaks than places that did have masks in place.” Two days later, on September 28, 2021, during a White House Press Briefing, you again stated that the Arizona study showed that masking in school resulted in a three and half times reduction in COVID-19 outbreaks. The same day, your official twitter account tweeted a similar statement. On October 13, 2021, during another White House Press Briefing, you again cited to the Arizona study as evidence in support of CDC mask guidance.
Following the publication of the study and your repeated public statements about it, The Atlantic, published an article that appeared to highlight a number of potential flaws with the study. Among the alleged flaws highlighted in the article were:
- The period of time selected for the study, July 15-August 31, 2021, resulted in data comparisons of schools that were open for as few as three weeks with schools that were open for as many as six weeks. According to the article, the schools without mask mandates were open longer than the schools with mask mandates;
- The study failed to determine whether the higher COVID-positive case rates in schools without mask mandates were actually due to transmission that occurred at school;
- County guidance potentially resulted in students at schools with mask mandates not being tested for COVID-19 at the same rate as students in schools without mask mandates. As the article notes, Maricopa County testing guidelines were defined by the mask status of the students in contact. Determining who to test based on masking status could lead to a potential detection bias; and
- The study failed to control for vaccination status in schools.
Following publication of the article, the authors of the study submitted a letter to The Atlantic taking issue with the flaws identified in the article. During a briefing with my staff, CDC asserted that it stood by the study and the authors’ rebuttal letter. When asked when CDC was provided with the rebuttal letter, CDC initially stated it had not received the rebuttal letter. CDC later clarified that it had in fact received the letter on February 3, 2022. The authors of the study, however, stated they sent CDC a copy of the letter “sometime the week of [December 20, 2021].”
Although CDC staff originally stated they stood by the study, you have recently made statements that appear to acknowledge the study’s flaws. According to an article published in Reason, during a closed door briefing before the House Energy and Commerce Committee, you “acknowledged the ‘limitations’ of the Arizona study, as well as other studies the CDC has relied upon to inform their [school masking] guidance…” The fact that you and the CDC appear to be willing to acknowledge potential flaws and limitations of this and other studies in nonpublic forums raises serious questions about CDC’s commitment to transparency.
CDC’s COVID-19 guidance has had and continues to have a direct impact on the lives of Americans as they attempt to navigate this pandemic. The lack of transparency from the CDC on pandemic policy throughout the past two years has been appalling. I request that you provide the following information and material by no later than March 15, 2021:
- Did CDC receive a copy of the study authors’ rebuttal letter to The Atlantic the week of December 20, 2021? If so, please explain why CDC apparently falsely stated it had not received a copy of the study authors’ rebuttal letter until February 3, 2022;
- All documents and communications referring or relating to the study;
- All documents and communications between the CDC and the authors of the study;
- All documents and communications referring or relating to Director Walensky’s use of the study in public statements on September 26, September 28, and October 13, 2021;
- All documents and communications referring or relating to the December 16, 2021 article published in The Atlantic;
- All documents and communications referring or relating to the study authors’ rebuttal to The Atlantic article;
- All documents and communications referring or relating to Director Walensky’s acknowledgement of the study’s limitations;
- A timeline on the CDC and MMWR review process for the study;
- An explanation of whether the study was put out prior to publication under a press embargo and, if so, the date of the embargo release; and
- A breakdown of the:
- Percentage of articles accepted by the MMWR during proposal phase out of number of proposals submitted;
- Percentage of articles rejected by the MMWR during the proposal phase out of number of proposals submitted;
- Percentage of articles rejected during each phase of the MMWR review process out of number of proposals accepted;
- Percentage of articles where during each phase of the MMWR review process CDC requires changes to methodology, data collection, data analysis or how a study is conducted out of number of proposals accepted;
- Percentage of articles that move for final approval and publication following the MMWR phase review process; and
- Percentage of articles rejected from final publication out of total articles that have completed the MMWR review process.
Thank you for your prompt attention to this matter.
Permanent Subcommittee on Investigations
cc: The Honorable Jon Ossoff
The Honorable Christi A. Grimm
Department of Health and Human Services