A CDC study pulled from MMWR in March under acting director Jay Bhattacharya was published in JAMA Network Open, finding the 2025-26 COVID shot cut hospitalization risk by 55% and ER or urgent-care visits by 50%.
The analysis used a test-negative design across 179 hospitals in seven states, comparing vaccinated shares among patients with COVID-like illness: 5% of COVID-positive urgent-care or ED patients were vaccinated versus 12% of COVID-negative controls.
Bhattacharya had blocked the paper after internal scientific and editorial review, arguing randomized controlled trials were the proper standard and the observational method was inadequate for vaccine-effectiveness assessment.
Researchers and outside critics said the same design is routinely used for seasonal vaccine monitoring when new randomized trials are impractical, making the publication a flashpoint over CDC scientific independence and COVID vaccine policy.
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COVID-19 Booster Effectiveness, Waning Immunity, and Uptake Trends: Data and Strategies for 2024–2026
Overview
As of mid-2026, updated COVID-19 boosters from the 2024-2025 and 2025-2026 seasons have shown strong effectiveness in protecting people from severe outcomes, especially against Omicron subvariants. These boosters are rigorously tested for safety and efficacy, and are recommended by the CDC for everyone aged 6 months and older. Real-world data, such as studies in U.S. military veterans, show that the 2024-2025 vaccine reduced major cardiovascular events and saved lives. Overall, these updated boosters play a key role in reducing the burden of disease and supporting public health.