CDC Postpones Study on Vaccine Effectiveness
The Centers for Disease Control and Prevention (CDC) was set to release a study last month indicating that coronavirus vaccines significantly reduce the likelihood of severe disease. However, Dr. Jay Bhattacharyya, the agency’s acting director, delayed the publication due to concerns regarding the study’s methodology.
The findings were initially slated for inclusion in the Morbidity and Mortality Weekly Report (MMWR), the CDC’s primary scientific journal. Andrew Nixon, a spokesperson for the Department of Health and Human Services, stated in an email that Dr. Bhattacharyya raised concerns about the observational methods employed in the study to ascertain vaccine effectiveness.
Nixon added that it is customary for CDC leadership to scrutinize any methodological concerns before MMWR papers are published. “Dr. Bhattacharyya seeks to ensure that these papers adhere to the most appropriate research methodologies,” he explained.
Health officials from the Trump administration have criticized the standard practices in vaccine research, questioning established methods that scientists have used for years. Many public health experts suspect this is part of a broader initiative to create uncertainty about vaccine safety and complicate access for the public.
The administration has pledged to restore what it terms the “gold standard of science” to federal health agencies. Critics argue this effort aims to dismiss research that contradicts the administration’s views on vaccines. Robert F. Kennedy Jr., who oversees the CDC, has a longstanding history of anti-vaccine activism.
Dr. Bhattacharyya, a political appointee who began his tenure in February, did not respond to requests for comments regarding the matter. However, a preliminary summary obtained by NBC News suggests that the upcoming vaccine formulation for 2025-2026 could reduce the risk of severe illness in adults by approximately 50%.
According to an epidemiologist at the CDC’s National Center for Immunization and Respiratory Diseases, the study is now anticipated to be published on March 19. An anonymous source, due to fears about job security, emphasized the unusual nature of a political appointee withholding a scientifically reviewed MMWR paper.
While publication of MMWR has been suspended under the Trump administration, typically it is rare for a single article to be completely withheld. A temporary communications freeze in January 2025 led to the CDC not releasing several MMWR documents, but these were eventually made public. Recent suspensions due to a government shutdown also occurred but were later resolved.
Fiona Havers, a former CDC medical epidemiologist, remarked on the significance of the case, noting that halting the publication of a scientifically reviewed report suggests a troubling level of political interference in the CDC’s scientific processes.
Havers resigned from the agency in June to protest the firing of the CDC’s Vaccine Advisory Committee under President Kennedy, followed by the appointment of individuals with vaccine-skeptical positions. A ruling by a judge later deemed that many of these selections were ineligible, thus halting the appointment process.
The disputed coronavirus study utilized a test-negative design methodology, comparing vaccination statuses between individuals who tested positive for COVID-19 and those who tested negative. This approach indicated that vaccinated individuals were less likely to require hospitalization. Notably, this methodology is commonly used in CDC reports, including those assessing the effectiveness of seasonal influenza vaccines.
Despite Bhattacharyya’s concerns, current and former CDC employees assert that alternatives are generally more costly and time-consuming. For example, cohort studies, which track vaccinated and unvaccinated individuals over an extended time frame, entail larger sample sizes and heightened expenses.
Additionally, some federal health officials advocate for more randomized controlled trials, a study design that compares vaccinated groups with placebo control groups. However, ethical dilemmas arise when withholding vaccines from participants who are entitled to approved vaccinations. The FDA previously approved the initial COVID-19 vaccines based on such trials.
Bhattacharyya has requested CDC officials to present an argument supporting test-negative designs and alternative methodologies at a late March meeting, though a timeline for the publication remains uncertain. Even if this paper does not make it to MMWR, its authors might seek publication in another reputable medical journal.
According to Nixon, the CDC is engaged in a scientific discussion regarding how best to measure vaccine efficacy across its publications, asserting that ensuring methodologically sound analyses is paramount to preventing errors in communication. He reaffirmed the agency’s commitment to transparency regarding the data and methodologies that inform its conclusions.
