CDC Blocks Publication of Report on COVID Vaccine Efficacy

The Centers for Disease Control and Prevention (CDC) has blocked the publication of a report that demonstrated the COVID-19 vaccine reduced emergency department visits and hospitalizations among healthy adults by approximately 50% during the previous winter. The report was initially scheduled for publication in the CDC’s Morbidity and Mortality Weekly Report (MMWR) on March 19, 2026, but was ultimately not accepted ^[1][2].

The decision to block the report was made by the acting CDC director, Jay Bhattacharya, who expressed concerns regarding the observational methodology used to estimate vaccine effectiveness. This intervention occurred after the report had already cleared the CDC’s scientific review process ^[2][3].

An HHS spokesperson, Andrew Nixon, stated that scientific reports undergo multiple levels of review, and the concerns about the methodological approach were the reason for the manuscript’s rejection ^[1][4].

Former CDC officials have described the decision as highly unusual, noting that halting an MMWR report at the publication phase after scientific clearance is rare ^[3][4].

What Is Known

The report indicated that the COVID-19 vaccine was effective in reducing hospital visits among healthy adults by about half during the last winter season. It had passed the CDC’s scientific review process before being blocked from publication. The acting CDC director cited methodological concerns as the reason for the decision ^[1][2][3].

What Remains Unclear

It remains unclear whether there were any additional factors influencing the decision to block the report, as some unconfirmed reports suggest potential political motivations. However, these claims have not been corroborated by independent sources ^[2][3].