• Home
  • Latest
  • Fortune 500
  • Finance
  • Tech
  • Leadership
  • Lifestyle
  • Rankings
  • Multimedia
PoliticsCDC

CDC blocks release of study on COVID vaccine effectiveness

By
Mike Stobbe
Mike Stobbe
and
The Associated Press
The Associated Press
Down Arrow Button Icon
By
Mike Stobbe
Mike Stobbe
and
The Associated Press
The Associated Press
Down Arrow Button Icon
April 23, 2026, 1:10 PM ET
cdc
A sign with the CDC logo is displayed at the entrance to the agency's headquarters in Atlanta on March 2, 2025. Miguel Martinez/Atlanta Journal-Constitution via AP, File

U.S. health officials stopped the publication of a study on whether the COVID-19 vaccine was keeping adults from becoming sick enough to have to go to the hospital.

Recommended Video

A U.S. Department of Health and Human Services spokesman on Wednesday confirmed the decision to halt publication, citing a dispute about the study’s methodology.

The research paper was to appear in Morbidity and Mortality Weekly Report, the Centers for Disease Control and Prevention’s flagship publication.

One way scientists have studied COVID-19 vaccine effectiveness is by focusing on sick people who were admitted to hospitals or visited emergency rooms. The researchers check whether patients were vaccinated and then calculate the odds of a positive COVID-19 test among vaccinated patients vs. those who were unvaccinated.

Papers using that methodology have been published — after review by experts in the field — in a number of esteemed journals, including Pediatrics and the New England Journal of Medicine.

Following the same approach, the new study concluded that the vaccine cut ER visits and hospitalizations among otherwise healthy adults by about half this past winter, according to The Washington Post, which first reported the cancellation.

HHS officials did not say exactly why that methodology was a problem in this instance but argued that prior infection, behavior and differences in who seeks care can affect results.

The wider scientific community does not have those concerns and many researchers have used the approach, said Dr. Fiona Havers, an Atlanta-based doctor who previously worked at CDC. The methodology is built to address differences related to who seeks care, and prior infection shouldn’t be much of an issue because so many Americans have been infected by the coronavirus, she added.

No study design is perfect, but HHS officials haven’t proposed an alternative “that’s realistic and ethical for getting real-time estimates of how well vaccines are working each year,” said Havers, who once led a CDC hospital network surveillance team that focused on COVID-19 and other respiratory viruses.

During President Donald Trump’s first administration, public health advocates worried that political appointees were trying to control what was being published in the MMWR.

Those concerns returned last year, when Trump returned to office and publication of the MMWR was temporarily suspended. It returned, but has remained a thinner version of its former self.

“Health care professionals rely on the MMWR for timely, objective and fact-based information about the nation’s public health,” said U.S. Sen. Dick Durbin, an Illinois Democrat who voiced concern when CDC communications were halted last year.

“Muzzling scientists and doctors on how to prevent Americans from being hospitalized can have deadly consequences. The CDC must abandon plans to place a political gag order on this critical research,” Durbin said in a statement Wednesday.

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.

The Fortune 500 Innovation Forum will convene Fortune 500 executives, U.S. policy officials, top founders, and thought leaders to help define what’s next for the American economy, Nov. 16-17 in Detroit. Apply here.
About the Authors
By Mike Stobbe
See full bioRight Arrow Button Icon
By The Associated Press
See full bioRight Arrow Button Icon

Latest in Politics

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025

Most Popular

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Fortune Secondary Logo
Rankings
  • 100 Best Companies
  • Fortune 500
  • Global 500
  • Fortune 500 Europe
  • Most Powerful Women
  • World's Most Admired Companies
  • See All Rankings
  • Lists Calendar
Sections
  • Finance
  • Fortune Crypto
  • Features
  • Leadership
  • Health
  • Commentary
  • Success
  • Retail
  • Mpw
  • Tech
  • Lifestyle
  • CEO Initiative
  • Asia
  • Politics
  • Conferences
  • Europe
  • Newsletters
  • Personal Finance
  • Environment
  • Magazine
  • Education
Customer Support
  • Frequently Asked Questions
  • Customer Service Portal
  • Privacy Policy
  • Terms Of Use
  • Single Issues For Purchase
  • International Print
Commercial Services
  • Advertising
  • Fortune Brand Studio
  • Fortune Analytics
  • Fortune Conferences
  • Business Development
  • Group Subscriptions
About Us
  • About Us
  • Lists Calendar
  • Press Center
  • Work At Fortune
  • Terms And Conditions
  • Site Map
  • About Us
  • Lists Calendar
  • Press Center
  • Work At Fortune
  • Terms And Conditions
  • Site Map
  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • Instagram icon
  • Pinterest icon

Latest in Politics

robert isom
InvestingAirline industry
American Airlines CEO calls United merger ‘a non-starter’: ‘No way to view that as anything but anti-competitive’
By Jake AngeloApril 24, 2026
2 hours ago
Feds charge U.S. Army soldier who made $400,000 from Polymarket bets tied to Maduro capture
LawPolymarket
Feds charge U.S. Army soldier who made $400,000 from Polymarket bets tied to Maduro capture
By Jeff John RobertsApril 23, 2026
10 hours ago
Jensen Huang stands smiling with his arms outstretched.
Big TechBillionaires
‘Don’t leave’: Jensen Huang challenges billionaire class as he insists ‘highest taxes in the world’ are OK with him
By Jacqueline MunisApril 23, 2026
12 hours ago
You can fly almost anywhere in Europe for €20 while Spirit Airlines is staving off bankruptcy. Here’s the difference
PoliticsAirline industry
You can fly almost anywhere in Europe for €20 while Spirit Airlines is staving off bankruptcy. Here’s the difference
By Catherina GioinoApril 23, 2026
12 hours ago
President Donald Trump
EconomyImmigration
People living in the U.S. with temporary protected status, targeted by Trump, are a $29 billion economic force
By Tristan BoveApril 23, 2026
14 hours ago
Pope Leo says he carries a photo of a slain Muslim boy in his pocket: ‘I cannot be in favor of war’
PoliticsWar
Pope Leo says he carries a photo of a slain Muslim boy in his pocket: ‘I cannot be in favor of war’
By Nicole Winfield and The Associated PressApril 23, 2026
14 hours ago

Most Popular

When interest on national debt overtook military spending, it triggered a limit where the U.S. may ‘cease to be a great power,’ warns Hoover historian
Economy
When interest on national debt overtook military spending, it triggered a limit where the U.S. may ‘cease to be a great power,’ warns Hoover historian
By Eleanor PringleApril 23, 2026
22 hours ago
Despite nearing their 60s, nearly four in 10 Americans heading towards the end of their careers don’t even have a retirement account
Success
Despite nearing their 60s, nearly four in 10 Americans heading towards the end of their careers don’t even have a retirement account
By Emma BurleighApril 23, 2026
18 hours ago
Officials will flush 50,000 toilets to flood a Utah lake in order to generate electricity
Environment
Officials will flush 50,000 toilets to flood a Utah lake in order to generate electricity
By Mead Gruver, Dorany Pineda and The Associated PressApril 22, 2026
2 days ago
Cursor’s 25-year-old CEO is a former Google intern who just inked a $60 billion deal with SpaceX
AI
Cursor’s 25-year-old CEO is a former Google intern who just inked a $60 billion deal with SpaceX
By Marco Quiroz-GutierrezApril 22, 2026
2 days ago
Craving work-life balance is a huge red flag, says Fortune 500 Europe CEO—and like Barack Obama, he happily works through weekends
Success
Craving work-life balance is a huge red flag, says Fortune 500 Europe CEO—and like Barack Obama, he happily works through weekends
By Orianna Rosa RoyleApril 22, 2026
2 days ago
The Iran war is pushing Southeast Asia to debate the once unthinkable: Whether ships will need to pay to transit the Strait of Malacca
Economy
The Iran war is pushing Southeast Asia to debate the once unthinkable: Whether ships will need to pay to transit the Strait of Malacca
By Angelica AngApril 23, 2026
22 hours ago

© 2026 Fortune Media IP Limited. All Rights Reserved. Use of this site constitutes acceptance of our Terms of Use and Privacy Policy | CA Notice at Collection and Privacy Notice | Do Not Sell/Share My Personal Information
FORTUNE is a trademark of Fortune Media IP Limited, registered in the U.S. and other countries. FORTUNE may receive compensation for some links to products and services on this website. Offers may be subject to change without notice.