CDC-Blocked COVID Vaccine Study Published in External Medical Journal, Shows 50% Reduction in Hospitalizations

A COVID-19 vaccine study blocked from publication in the CDC's MMWR by acting director Jay Bhattacharya was published on June 23, 2026, in JAMA Network Open. The study, which analyzed patients across seven states in late 2025, found that the 2025-26 vaccine formulation reduced hospitalizations by 55%. While Bhattacharya cited methodological concerns with the test-negative design, some experts viewed the block as political interference under HHS Secretary Robert F. Kennedy Jr.

CDC publication block

• ▪A COVID-19 vaccine study blocked from publication in the CDC's Morbidity and Mortality Weekly Report by acting director Jay Bhattacharya was published on June 23, 2026, in JAMA Network Open.
• ▪Acting CDC Director Jay Bhattacharya blocked the study's publication in March 2026 after it had already undergone scientific review and approval by Morbidity and Mortality Weekly Report editors.

Test-negative study design

• ▪Limitations of the test-negative design include potential bias from participants having higher trust in the medical system and negative-testing participants having other respiratory illnesses.
• ▪The study utilized a test-negative design comparing the vaccination status of symptomatic patients who tested positive for COVID-19 to those who tested negative.
• ▪The test-negative design is considered by authors and outside researchers as a convenient, efficient, and cost-effective method to evaluate vaccines in real-world settings.

COVID vaccine effectiveness findings

• ▪The study found that the 2025-26 COVID-19 vaccine formulation reduced the odds of COVID-related emergency room or urgent care visits by 50% and hospitalizations by 55%.
• ▪The study analyzed symptomatic adults visiting hospitals or urgent care clinics across seven states from September to December 2025.

Political interference concerns

• ▪Health and Human Services Secretary Robert F. Kennedy Jr., who oversees the CDC, has a history of anti-vaccine activism and previously called the COVID-19 vaccine the deadliest vaccine ever made.
• ▪Some public health experts viewed acting CDC Director Jay Bhattacharya's withdrawal of the study as political interference or an attempt to withhold evidence of vaccine safety.

Scientific methodology debate

• ▪Acting CDC Director Jay Bhattacharya argued that longitudinal cohort studies provide a stronger design than test-negative studies, though experts note cohort studies are more expensive and time-consuming.
• ▪Health and Human Services Department spokesperson Emily Hilliard stated that ensuring methodological soundness and clear communication is preferable to risking error when findings influence clinical decisions.
• ▪Natalie Dean of Emory University stated that researchers have long recognized the limitations of test-negative studies but agree they do not undermine the conclusions.

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