CDC Delays Publication of COVID-19 Vaccine Effectiveness Report

The Centers for Disease Control and Prevention (CDC) delayed the publication of a report indicating that COVID-19 vaccinations significantly reduced emergency department visits and hospitalizations among healthy adults between September and December 2025. The report, which had cleared the CDC’s scientific-review process, was initially scheduled for release on March 19, 2026, in the Morbidity and Mortality Weekly Report (MMWR) ^[1][2].

Acting CDC Director Jay Bhattacharya postponed the report, expressing concerns about the methodology used, known as the test-negative design. This methodology has been a standard approach in CDC and peer-reviewed studies for assessing vaccine effectiveness, including a flu vaccine report published in the MMWR just a week prior ^[1][3].

According to a spokesperson for the Department of Health and Human Services, Andrew Nixon, it is routine for CDC leadership to review and flag methodological concerns in MMWR papers before publication. Nixon stated that Bhattacharya aims to ensure the most appropriate methodology is employed ^[1].

What Is Known

The delayed report showed that COVID-19 vaccinations reduced emergency department and urgent care visits by approximately 50% and hospitalizations by about 55% among healthy adults during the specified period ^[1][2]. The test-negative design used in the report is a widely accepted method for evaluating vaccine effectiveness ^[3].

What Remains Unclear

Unconfirmed reports suggest that the delay may be linked to internal policy discussions regarding vaccine availability for children, although these claims have not been corroborated by multiple sources ^[4]. The exact reasons for the acting director’s concerns about the methodology remain unspecified beyond the general statement of ensuring methodological appropriateness ^[1].