{"id":8212,"date":"2026-04-10T22:24:18","date_gmt":"2026-04-10T22:24:18","guid":{"rendered":"https:\/\/globalnewstoday.uk\/index.php\/2026\/04\/10\/acting-cdc-director-delayed-release-of-study-showing-benefit-of-covid-vaccines-nbc-news\/"},"modified":"2026-04-10T22:24:18","modified_gmt":"2026-04-10T22:24:18","slug":"acting-cdc-director-delayed-release-of-study-showing-benefit-of-covid-vaccines-nbc-news","status":"publish","type":"post","link":"https:\/\/globalnewstoday.uk\/index.php\/2026\/04\/10\/acting-cdc-director-delayed-release-of-study-showing-benefit-of-covid-vaccines-nbc-news\/","title":{"rendered":"Acting CDC director delayed release of study showing benefit of Covid vaccines – NBC News"},"content":{"rendered":"

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The CDC was expected last month to publish a study showing that Covid vaccines reduced the likelihood of severe illness, but the agency\u2019s acting director, Dr. Jay Bhattacharya, delayed its release due to concerns about the methodology.
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The study was scheduled to come out in the Centers for Disease Control and Prevention\u2019s flagship scientific publication, the Morbidity and Mortality Weekly Report (MMWR). But Andrew Nixon, a spokesperson for the Department of Health and Human Services, said in an email that Bhattacharya \u201cexpressed concerns about the observational method used in this study to calculate vaccine effectiveness.\u201d
\u201cIt\u2019s routine for CDC leadership to review and flag concerns about MMWR papers, especially relating to their methodology, leading up to planned publication,\u201d Nixon said. \u201cDr. Bhattacharya wants to make sure that the paper uses the most appropriate methodology for such a study.\u201d
Top health officials in the Trump administration have criticized the way that vaccine research is typically conducted, calling into question methods that have been used for decades and are widely accepted among scientists. Many public health experts see this as part of a broader effort to sow doubt in vaccine safety and make vaccines less available to the public.
Although the Trump administration has pledged to restore what it calls \u201cgold-standard science\u201d to federal health agencies, some experts say the aim is to invalidate studies that don\u2019t align with the administration\u2019s views on vaccines. Health Secretary Robert F. Kennedy Jr., who oversees federal health agencies including the CDC, has a long history of anti-vaccine activism.
Bhattacharya, a political appointee who was tapped to run the CDC in February<\/a> until Trump nominates a permanent director, did not respond to a request for comment.
A preliminary summary of the study\u2019s results viewed by NBC News suggested that the 2025-26 Covid vaccine formulation reduced the likelihood of severe illness by about half among adults.
An epidemiologist in the CDC\u2019s National Center for Immunization and Respiratory Diseases, who asked not to be named due to concerns about job security, said the paper was due to come out March 19.
The Washington Post was first to report the news<\/a> of the delay.
The epidemiologist and two former CDC employees said it\u2019s very unusual for a political appointee within the agency such as Bhattacharya to hold back an MMWR paper that had undergone scientific review and was approved by the publication\u2019s editors.
Publication of the MMWR journal has been paused under Trump before, but it\u2019s much rarer for one paper to get pulled. The CDC held the release of some MMWR papers<\/a> in January 2025, when the Trump administration imposed a temporary communication freeze. The publication was again paused in the fall due to the government shutdown and layoffs of MMWR staff, which were later reversed.
\u201cI\u2019m not saying that they haven\u2019t stopped other publications or forced changes to them, but to wholesale stop this report from coming out, given that it is such a well-established platform and such a well-established methodology, does strike me as a new level of political interference into CDC\u2019s scientific process,\u201d said Fiona Havers, a former medical epidemiologist at the CDC who oversaw the agency\u2019s Covid hospitalization data.
Federal judge blocks RFK Jr.'s vaccine schedule changes
Havers resigned from the CDC in protest in June after Kennedy fired the agency\u2019s vaccine advisory committee and appointed a new group, many of whom are skeptical of vaccines. (A judge has since ruled that most of Kennedy\u2019s selections were unqualified<\/a> and put their appointments on hold.)
The Covid paper that Bhattacharya took issue with relied on a methodology known as a test-negative design, according to one former and one current CDC employee familiar with it. The researchers had compared the vaccination status of people who tested positive for Covid to the vaccination status of people who tested negative, showing that people who had received Covid shots were less likely to be hospitalized or visit the emergency department. Several of the journal\u2019s editors and at least two of the paper\u2019s authors could not be reached for comment.
Current and former CDC employees said that\u2019s a common way to evaluate the effectiveness of vaccines. Many other MMWR papers, including a March 12 report<\/a> on the effectiveness of seasonal flu shots and a December report<\/a> on the effectiveness of Covid vaccines in children, have used the same methodology. An HHS official said Bhattacharya did not assume his acting director role in time to vet the flu vaccine paper but would have raised the same concern.
Other methodologies are either too expensive or wouldn\u2019t produce timely results, current and former CDC scientists said. For example, a type of design known as a cohort study \u2014 which tracks vaccinated and unvaccinated people over time, then compares the rates of illness \u2014 is far costlier and typically requires a larger sample size and longer follow-up period.
Several top federal health officials have called for more randomized controlled trials \u2014 another type of study design, which for vaccine research would compare a group of vaccinated people to a group that got a placebo. But in the case of Covid shots, the method poses ethical concerns because such a trial would require withholding an approved vaccine from some participants. The first Covid vaccines were evaluated in randomized controlled trials, and the resulting data led to their approval by the Food and Drug Administration.
\u201cYou can\u2019t do randomized controlled trials every year once a vaccine is licensed and proven to be effective,\u201d Havers said.
The CDC epidemiologist said agency employees gave a presentation in late March, at Bhattacharya\u2019s request, explaining the test-negative design and why other methodologies weren\u2019t as efficient. But there has been no resolution yet as to when, or if, the study will be published by the agency, the employee said.
If the paper does not wind up published in MMWR, it\u2019s possible its authors could still submit it for publication in an independent medical journal.
Nixon said the CDC \u201cengages in scientific discourse on how best to measure vaccine effectiveness across all CDC publications,\u201d and that \u201ctaking time to ensure analyses are methodologically sound and clearly communicated is always preferable to risking error.\u201d
He added that the agency \u201cremains committed to timely publication and to transparency about the data and methods that underpin its conclusions.\u201d
Aria Bendix is the breaking health reporter for NBC News Digital.
© 2026 NBCUniversal Media, LLC<\/p>\n

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