A CDC-blocked study on COVID-19 vaccine effectiveness using a test-negative design has now been published in JAMA Network Open, showing vaccination cut emergency department visits and hospitalizations by about half during the winter season.

There’s ongoing debate about the study design, with critics raising potential biases from prior infection and behavior, while supporters say no design is perfect and this method helps address care-seeking differences.

Authors and supporters stress the importance of continuing to publish VE estimates in populations with evolving immunity and different circulating strains.

The article is sourced from AP reporting by Mike Stobbe, dated June 23, 2026, and notes the study links to the JAMA Network Open article for full details.

AP context explains the broader political and methodological tensions behind the study’s initial suppression and eventual publication.

An editorial by Natalie Dean highlights the test-negative design’s practicality for ongoing vaccine monitoring and urges sensitivity analyses to gauge bias and confounding.

Context includes related discussions at a recent CDC forum and the involvement of figures like Martin Kulldorff and Bhattacharya in vaccine policy debates.

An accompanying editorial defends the test-negative design as a standard, efficient tool in respiratory vaccine surveillance, acknowledging its limitations such as possible confounding by health-seeking behavior while emphasizing practicality.

The piece notes the test-negative design remains valuable for estimating VE by using patients seeking care as controls, avoiding the need for a fully enumerated population denominator.

The publication highlights a conflict with a government health journal, underscoring issues in editorial decision-making or vetting within official channels.

The study drew on data from 85,725 ED/urgent care visits and 26,073 hospitalizations across hundreds of facilities in seven states, covering Sept–Dec 2025.

Overall, the report frames tensions between data transparency, methodological debates, and real-time VE assessment amid a changing pandemic landscape.