Leaked CDC Report Reveals RFK Jr Officials Blocked Flagship Medical Journal From Publishing Positive Covid Vaccine Data

A completed CDC study showing Covid-19 vaccines cut hospitalisations and emergency department visits among healthy adults by roughly half has been blocked from publication in the agency's flagship scientific journal, according to three people with direct knowledge of the decision.

The report had cleared the CDC's full internal scientific-review process, which involves dozens of scientists, and had been scheduled for publication on 19 March 2026 in the Morbidity and Mortality Weekly Report (MMWR), the journal American public health officials have relied upon for more than 70 years. Instead, acting CDC director Jay Bhattacharya first delayed it and, as of 22 April 2026, a formal rejection letter had been issued to the report's authors.

Current and former CDC officials say it is extraordinarily rare for a paper to be pulled at that stage. The episode has deepened an already fraught debate over whether Health Secretary Robert F. Kennedy Jr., a longtime critic of Covid vaccines, is allowing political priorities to override scientific ones.

What the Blocked Report Found and Why the MMWR Matters

The suppressed study, compiled using what researchers call a test-negative design, examined people who visited emergency departments and hospitals last winter with respiratory symptoms. It compared the vaccination status of those who tested positive for Covid-19 against those who tested negative for the virus. The analysis found that vaccinated healthy adults were approximately 50 per cent less likely to be hospitalised or require emergency treatment.

Vaccine effectiveness estimates derived from this method have been published repeatedly in the New England Journal of Medicine, the Lancet, JAMA Network Open, and Pediatrics, as well as in the MMWR itself, without methodological controversy.

The MMWR, published continuously since 1952 by the Centers for Disease Control and Prevention, is the primary channel through which the agency communicates real-time surveillance data and public health recommendations to clinicians and policymakers. Blocking a paper there does not simply delay a single finding. It removes it from the standard scientific pipeline that clinicians use to make treatment and vaccination decisions.

'This network has published in New England Journal of Medicine and The Lancet and all of these other very high-profile journals in the past,' said Dr. Fiona Havers, who resigned as a senior vaccine policy adviser at the CDC in June 2025 over Kennedy-era changes to vaccine policy. 'This seems like pretty aggressive interference by a political appointee into CDC scientific processes.'

From Delay to Outright Rejection

The Washington Post first reported two weeks earlier that Bhattacharya, who also holds the directorship of the National Institutes of Health, had delayed publication of the study. At that point, HHS spokesman Andrew Nixon told the Post it was 'routine for CDC leadership to review and flag concerns about MMWR papers, especially relating to their methodology, leading up to planned publication,' and said Bhattacharya had flagged concerns about 'the observational method used in the study to calculate vaccine effectiveness.' Following that report, Bhattacharya met with the study's authors, who declined to change their methodology.

In late March 2026, CDC scientific staff gave a presentation at Bhattacharya's request specifically explaining the test-negative design and why alternative methodologies were less efficient for measuring real-time vaccine effectiveness, as NBC News reported. There was still no resolution. On 21 April 2026, the study's authors received a formal rejection letter from the MMWR.

The following day, Nixon gave CNN a different account of events than the one he had provided two weeks before: 'Scientific reports are routinely reviewed at multiple levels to ensure they meet the highest standards before publication. The MMWR's editorial assessment identified concerns regarding the methodological approach to estimating vaccine effectiveness and the manuscript was not accepted for publication.'

That framing, presenting the rejection as a standard editorial decision, directly contradicts the accounts of the three people familiar with the process who spoke to the Washington Post. It also sits uneasily against one specific fact: a study on flu vaccine effectiveness using the identical test-negative methodology was published in the MMWR just one week before the Covid paper was scheduled to appear. The HHS, when asked about that parallel, said Bhattacharya had not been in a position to review the influenza paper and would have raised the same concerns had he seen it.

Former CDC Officials: This Has Not Happened Before

The reaction from scientists who have worked inside the CDC has been pointed and consistent. Michael Iademarco, who directed the CDC centre with oversight of the MMWR from 2014 to 2022, told the Washington Post: 'I cannot recall CDC stopping an MMWR report in the publication phase after scientific clearance and editorial review. On rare occasions we shifted the timing slightly to better align communications plans with competing or reinforcing pieces.' Dr. Demetre Daskalakis, the former director of the CDC's National Centre for Immunisation and Respiratory Diseases, was equally blunt in an emailed statement to CIDRAP: 'Suppressing the standard of science on VE [vaccine efficacy] to wait for a perfect study in a system that cannot support it is not a hallmark of transparent scientific expertise.'

Dr. Deb Houry, who served as the CDC's chief medical officer until she resigned in August 2025 in solidarity with ousted CDC director Susan Monarez, told CNN: 'His request for a change in methodology is really too late after the fact. In general, their methodology was appropriate and has been used in other studies. I reviewed MMWR as in my role as acting principal deputy and chief medical officer for approximately four years, and I very rarely rejected a paper late this in the process.' Monarez herself, who was fired by Kennedy early in her tenure after refusing to pre-approve vaccine advisory panel recommendations made by his hand-picked appointees, later wrote in a Wall Street Journal opinion piece that she had been directed to rubber-stamp those recommendations.

The timing adds further context that is difficult to ignore. The Trump administration has been actively working to moderate its public posture on vaccines ahead of the 2026 midterm elections, after Republican pollsters warned of the political risks associated with vaccine scepticism.

A study that passed every scientific review the CDC has is now a rejection letter. The scientists who wrote it have not changed a word.