As regulatory uncertainty around COVID vaccines continues to swirl, a new report from the Centers for Disease Control and Prevention (CDC) showcases the benefits of the immunizations among children.
The CDC’s Dec. 11 edition of its Morbidity and Mortality Weekly Report tracked electronic health records from seven health care systems across the U.S. to measure the effectiveness of COVID vaccines, finding that the 2024-2025 version of the shots were effective in protecting children from COVID infection-associated hospital trips.
Among children aged 9 months to 4 years, the vaccine was determined to be 76% effective at preventing visits to an emergency department or urgent care (ED/UC) for COVID, according to the data. Effectiveness among children ages 5 to 17 on the same measure was 56%, the CDC found.
“These findings suggest that vaccination with a 2024–2025 COVID-19 vaccine dose provided children with additional protection against COVID-19–associated ED/UC encounters compared with no 2024–2025 dose,” the CDC concluded (PDF).
The 2024-2025 updated COVID vaccines from Pfizer and Moderna became available in Aug. 22, 2024. The CDC’s data tracking ran from Aug. 29, 2024, to Sept. 2, 2025, according to the report.
Those shots fell under the CDC’s Advisory Committee on Immunization Practices (ACIP) guidance from last June, which recommended that all people more than 6 months of age receive COVID vaccination for protection against severe infection.
More recently, the CDC switched up on its previously broad recommendations. As of October, the agency’s updated immunization schedule applies an individual-based decision-making process to COVID vaccines, meaning that people are recommended to consult a doctor or other healthcare provider before deciding to receive the shot.
The impact that this change will have on COVID vaccination effectiveness in children is “unclear,” the CDC noted in its MMR report, which highlights the importance of continued monitoring.
The report comes shortly after the head of the FDA’s Center for Biologics Evaluation and Research (CBER), Vinay Prasad, M.D., outlined the agency’s plans to direct vaccine regulation toward “evidence-based medicine” in an internal email to CBER staffers.
In the message, Prasad added that the FDA “will acknowledge that COVID-19 vaccines have killed American children,” claiming that “no fewer than 10” children have died from using the vaccines. In making the claim, the FDA official cited a “detailed analysis of deaths voluntarily reported" to a federal database between 2021 and 2024, he wrote.
The website for that database, the Vaccine Adverse Event Reporting System, carries a disclaimer warning that the data alone "cannot be used to determine if a vaccine caused or contributed to an adverse event or illness." In the memo, Prasad wrote that the conclusion was based on a months-long review of 96 deaths reported between 2021 and 2024, adding that the FDA would take “swift action regarding this new safety concern.”
The FDA action may come in the form of a black box warning on COVID vaccines, two people familiar with the agency’s plans told CNN.
A black box warning is the FDA’s most serious safety signal. According to CNN, the plan for the warning is expected to be revealed by the end of the year, but it remains unclear which vaccines or age groups the warning might involve.
MRNA COVID vaccine makers Moderna and Pfizer have both emphasized the safety and effectiveness of their shots in separate statements.