A long-delayed study on COVID-19 vaccine effectiveness has finally seen the light of day, published Tuesday in JAMA Network Open, after being blocked from appearing in the Centers for Disease Control and Prevention's flagship journal by Trump administration political appointees.
The research found that the vaccines were roughly 55% effective at preventing COVID-19-associated hospitalizations and reduced emergency department and urgent care visits by about 50%. While these findings align with a broad body of evidence supporting vaccine efficacy, the study became a flashpoint in the ongoing political battle over pandemic response and scientific integrity.
The paper was originally slated for publication this spring in the Morbidity and Mortality Weekly Report (MMWR), the CDC's primary outlet for timely public health data. It had cleared the agency's internal scientific review but was flagged by acting CDC Director Jay Bhattacharya, a Trump appointee and co-author of the controversial Great Barrington Declaration. Bhattacharya argued the study's "test-negative design" was too vulnerable to false assumptions, potentially yielding skewed results. The CDC's chief science officer, Althea Grant-Lenzy, told the AP that Bhattacharya's intervention did not kill the paper but required authors to address his concerns—a process that ultimately led them to seek publication elsewhere.
The test-negative design is a long-established epidemiological method used to estimate vaccine effectiveness in real time. It compares vaccination rates among patients who test positive for a disease (like COVID-19) against those who test negative, adjusting for factors like healthcare-seeking behavior. Critics, including Bhattacharya and biostatistician Martin Kulldorff, contend the method relies too heavily on untested assumptions and can be distorted by prior infections or differences in patient groups. Proponents, however, argue it's the best available tool for tracking vaccine performance amid evolving viral strains and population immunity.
Emory University biostatistician Natalie Dean, in a commentary accompanying the study, stressed that "it is critical that we continue to characterize and publish estimates of vaccine effectiveness in populations with changing immunity against evolving viral strains." Dean was one of three panelists at a recent CDC forum on the methodology's strengths; the fourth panelist was Kulldorff, who reiterated his concerns.
The controversy echoes broader tensions between career scientists and political appointees over pandemic data. U.S. Health Secretary Robert F. Kennedy Jr. appointed Kulldorff last year to lead a federal vaccine advisory committee before he moved to an HHS planning role. Meanwhile, the Trump administration's handling of the study has drawn comparisons to other political interventions in health science, including the declassification of Fauci files and ongoing disputes over the origins of COVID-19.
During the CDC forum, an audience member shouted "We were in a pandemic! That's why!" when Kulldorff questioned why longer-term studies weren't used to evaluate the vaccines. The exchange underscored the urgency that drove widespread reliance on test-negative designs during the public health emergency.
Despite the methodological debate, many public health researchers maintain that no study design is perfect and that HHS officials have not proposed a realistic alternative for obtaining real-time vaccine effectiveness estimates. The study's publication in a peer-reviewed journal like JAMA Network Open—which also publishes research on topics such as GLP-1 drugs and male fertility—reinforces its scientific legitimacy.
The episode highlights the persistent friction between political oversight and scientific independence, a theme that continues to shape public health policy as the nation grapples with the legacy of the pandemic. For now, the data are finally public, offering fresh evidence that vaccines remain a critical tool against severe COVID-19 outcomes.
