COVID-19 Vaccine Study Published After CDC Publication Dispute
A COVID-19 vaccine effectiveness study that was previously blocked from appearing in the CDC’s Morbidity and Mortality Weekly Report has now been published in a medical journal. The study found that the updated 2025–2026 COVID-19 vaccine reduced the risk of emergency, urgent care, and hospital visits related to COVID-19 among adults.
The research examined more than 85,000 emergency department and urgent care encounters in seven states between September and December 2025. Using a test-negative case-control design, researchers compared patients who tested positive for SARS-CoV-2 with patients who had similar symptoms but tested negative. After adjusting for factors such as age, sex, and ethnicity, the study estimated that vaccination reduced COVID-19-related emergency or urgent care visits by 50% and hospitalizations by 55%.
Among adults aged 65 and older, the vaccine was estimated to reduce emergency or urgent care visits by 48% and hospitalizations by 53%. Researchers said the findings suggest that updated vaccination can still offer protection even for people who have previously been infected or vaccinated.
The study had already completed scientific review and received editorial approval before Acting CDC Director Jay Bhattacharya stopped its publication in April. Bhattacharya has questioned the use of test-negative studies, arguing that longitudinal cohort studies may provide stronger evidence for vaccine effectiveness. The Department of Health and Human Services said federal agencies must apply high standards of scientific rigor, particularly when findings could influence immunization decisions.
Outside experts noted that test-negative designs are widely used to assess vaccines for respiratory viruses, including influenza and COVID-19, though they have limitations such as possible incomplete vaccination records or other unmeasured differences among patients.
The episode has drawn attention to how federal agencies evaluate and release vaccine research. Scientists quoted in the report said methodological disagreements are common, but should generally be addressed through open scientific critique, replication, and publication rather than withholding completed studies.