CDC Delays Report on COVID-19 Vaccine Reducing ER Visits and Hospitalizations by Half

The Centers for Disease Control and Prevention delayed releasing a report on the effectiveness of the 2024–2025 COVID-19 vaccine in reducing emergency department visits and hospitalizations among adults in the United States from September 2024 to January 2025. According to CDC data, the vaccine reduced emergency visits by 33% and hospitalizations by 45% to 46%, falling short of claims that it halved these outcomes.

This estimate, based on data collected from September 2024 through January 2025, was derived from a single CDC-funded vaccine effectiveness network, according to the CDC’s Morbidity and Mortality Weekly Report (MMWR) volume 74 released in early 2025.

The Centers for Disease Control and Prevention’s interim analysis found that the 2024–2025 COVID-19 vaccine was 33% effective in preventing COVID-19–associated emergency department or urgent care visits among adults aged 18 and older.

The CDC’s report detailed that vaccine effectiveness (VE) against emergency department and urgent care visits was 33%, with a 95% confidence interval ranging from 28% to 38%, during the first 7 to 119 days following vaccination. This finding contrasts with claims that the vaccine halved such visits, as the data indicate a more modest reduction.

Regarding hospitalizations, the CDC analyzed data from two CDC-funded vaccine effectiveness networks focusing on immunocompetent adults aged 65 and older. The vaccine was found to be 45% to 46% effective in preventing COVID-19–related hospital admissions in this group. One network reported a VE of 45% with a 95% confidence interval of 36% to 53%, while the other showed 46% VE with a wider confidence interval of 26% to 60%. These figures also fall short of the 50% reduction in hospitalizations that some had suggested.

The report additionally included data on immunocompromised adults aged 65 and older from one CDC network, which showed a vaccine effectiveness of 40% against hospitalizations, although the confidence interval for this estimate was not specified. The estimates for hospitalizations similarly covered the same 7 to 119-day post-vaccination window as the emergency department and urgent care visits.

The interim estimates published in the MMWR were based on data collected between September 2024 and January 2025, encompassing the early months following the vaccine’s rollout for the 2024–2025 season. The CDC’s analysis focused exclusively on U.S. adults, with no data included for pediatric or other age groups. Comparisons were made between vaccinated individuals and those who did not receive the 2024–2025 COVID-19 vaccine dose.

Contrary to some reports, the CDC’s documentation does not indicate any delay in releasing these findings. The MMWR publication, identified as volume 74, mm7406a1, provides verified interim vaccine effectiveness data without noting any postponement. The report’s authors emphasized that the estimates represent short-term effectiveness within the specified post-vaccination period.

The vaccine effectiveness networks involved in the study are funded by the CDC and include one network assessing emergency department and urgent care visits among adults 18 years and older, two networks evaluating hospitalizations among immunocompetent adults aged 65 and older, and one network focusing on immunocompromised adults in the same age group. These networks collect and analyze clinical and laboratory data to estimate vaccine performance against COVID-19 outcomes.

The CDC’s interim report underscores the vaccine’s moderate effectiveness in reducing COVID-19–associated emergency visits and hospitalizations but does not support claims of a 50% or greater reduction in these outcomes. The findings provide a data-driven assessment of vaccine impact during the early months of the 2024–2025 vaccination period.

The CDC continues to monitor vaccine effectiveness as additional data become available and as the COVID-19 virus evolves. Future updates are expected as more comprehensive analyses are conducted across broader populations and longer follow-up periods.