What to know about COVID-19 study that was finally published after being blocked by CDC

Key Points:

• A CDC-led study published in JAMA Network Open found the 2025-26 COVID-19 vaccine reduced hospitalization risk by 55% and emergency visits by 50% among adults without weakened immune systems during fall and winter 2025.
• The study was initially blocked from CDC's Morbidity and Mortality Weekly Report due to concerns over its test-negative design methodology, which the CDC acting director publicly questioned.
• Experts argue the test-negative design is a valid and established method for assessing vaccine effectiveness, and some criticize the CDC for impeding the study’s publication, potentially hindering public understanding of vaccine benefits.
• The CDC and HHS emphasize the importance of rigorous review and scientific scrutiny before publication, while critics highlight the political influence of HHS Secretary Robert F. Kennedy Jr., a known COVID-19 vaccine skeptic.
• Health officials and vaccine experts reaffirm that COVID-19 vaccines remain safe and effective in preventing severe illness, hospitalization, and death, consistent with findings since the vaccines’ initial rollout in 2020.