A study examining how well the COVID-19 vaccine works has become the focus of attention in the United States, not only for its findings but for the way it was handled before publication. According to the report, the study has now been released in the peer-reviewed JAMA journal, after it had originally been blocked from appearing in a regular report issued by the Centers for Disease Control and Prevention.
The findings themselves were described as consistent with what scientists already understood. According to the report, the study found that the COVID-19 vaccine in the 2025-2026 season was about 55 percent effective against COVID hospitalizations, and that it was effective at reducing visits to urgent care centres and emergency departments. Experts cited in the segment said the science in the study was not surprising.
The dispute centred on where and whether the study would be published. According to the report, the research was supposed to appear in the March edition of the CDC publication that has been used for decades, and it had already passed an internal review. Instead, the study was held back before later being made available through the JAMA journal for everyone to read.
The decision to block it was attributed to a specific official. According to the report, the acting director of the CDC, Jay Bhattacharya, took issue with the study. His objection was not with the conclusions but with the method used, specifically the type of study design the researchers had relied on to measure how effective the vaccine was.
At the heart of the disagreement was a choice between two research approaches. According to the report, the study used what is known as a test-negative design, an observational method in which researchers look at people who go to a healthcare facility and ask who had received the vaccine and who had not. The acting director instead wanted a randomized controlled trial, a different approach to testing effectiveness.
Specialists quoted in the report pushed back on that preference. According to the report, a randomized controlled trial is slower and more expensive, and experts argue it is not always ethical to give people a placebo when a known vaccine may work. They added that the test-negative design is not fringe or radical but has been used for decades to study vaccine effectiveness, including for the flu shot, with the CDC having put out a test-negative study about the flu shot just one month earlier.