CDC Acting Director Delayed Vaccine-Effectiveness Paper Over Methodology Concerns

The CDC’s acting director, Dr. Jay Bhattacharya, reportedly delayed the release of an MMWR study showing Covid vaccines reduce severe illness, citing concerns about the observational method; the paper, based on a test‑negative design, was expected to indicate about a 50% reduction in severe outcomes among adults with the 2025‑26 vaccine formulation. Officials say leadership routinely reviews papers for methodological issues, while critics within and around the Trump administration have framed vaccine research debates as political interference. If the MMWR paper isn’t published, the authors could submit the findings to a medical journal after further analysis.