More than half of U.S. states are rejecting recent changes made by the Centers for Disease Control and Prevention to its child vaccine schedule.

Twenty-seven states say they are rejecting the changes, which include shifting hepatitis A vaccination from routine to situational.

“The science is clear,” Dr. Robbie Goldstein, public health commissioner in Massachusetts, said in a Jan. 14 statement as officials announced they would use a competing schedule compiled by the American Academy of Pediatrics. “Vaccines remain one of the most effective tools we have to prevent serious illness and save lives. In Massachusetts, we will continue to lead with integrity, transparency, and an unshakeable commitment to protecting children’s health and well-being.”

A spokesperson for the Department of Health and Human Services (HHS), the CDC’s parent agency, criticized the states in an email to The Epoch Times, describing them as having “imposed unscientific school closures, toddler mask mandates, and vaccine passports during the COVID era” and “destroyed public trust in public health.”

“The updated CDC childhood schedule continues to protect children against serious diseases while aligning U.S. guidance with international norms,“ the spokesperson said. ”Many peer nations achieve high vaccination rates without mandates by relying on trust, education, and strong doctor-patient relationships. Americans voted for transparency and HHS is delivering it.”

Blocs formed by states led by Democrats have vowed not to adopt the CDC changes. Some Republican-led states are also rejecting the updated schedule, a review of public statements and emails from officials found.

Some states, such as Idaho and Missouri, are pointing to state law, which prohibits changes without approval from legislators.

Others are aligning with the American Academy of Pediatrics, which partners with vaccine manufacturers and in 2025 ended a decades-old tradition of offering a schedule that was virtually the same as the CDC, and is planning to sue over the new changes. Many states have criticized how the CDC developed the updated schedule.

“This change to U.S. childhood vaccine schedule did not follow established procedures for vaccine recommendations. This change also creates confusion for families already trying to navigate a complex system and sows doubt about the effectiveness and science behind vaccines,” the Northeast Public Health Collaborative, which includes New York and Rhode Island, said in a Jan. 12 statement.

“Historically, the U.S. childhood immunization schedule has been updated regularly based on rigorous, expert-driven risk-benefit analysis of new data. These latest recommendations threaten to leave the American public, especially children, more vulnerable to preventable illness and death.”

Changes to the schedule are usually outlined during meetings of the CDC’s vaccine advisory panel. All of the members currently serving were selected by Health Secretary Robert F. Kennedy Jr.

Federal officials bypassed that committee while responding to a directive from President Donald Trump to study vaccine schedules in other countries and determine whether U.S. guidance should be updated.

The states rejecting the changes are California, Colorado, Connecticut, Delaware Hawaii, Idaho, Illinois, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, and Wisconsin.

Only two states—Louisiana and Montana—have said or suggested they will be adopting the changes.

Five others—Arkansas, Arizona, Indiana, South Carolina, and South Dakota—said they will review the updated recommendations.

The remaining states did not respond to inquiries and did not appear to have made public statements on the matter.

Some health institutions, including Seattle Children’s Hospital, have also said they will reject the new CDC schedule.

Kennedy and others announced the changes on Jan. 5. The updated schedule only broadly recommends eight vaccines for children, down from 14.

The update was based on a review by epidemiologists Dr. Tracy Beth Hoeg and Martin Kulldorff, who work for HHS divisions.

Recommendations for vaccines against measles and polio, among others, remain unchanged.

But recommendations for shots against diseases such as hepatitis A and rotavirus lacked international consensus and there are concerns about vaccine safety that need addressed through studies and trials, Hoeg and Kulldorff said in their review.

“After an exhaustive review of the evidence, we are aligning the U.S. childhood vaccine schedule with international consensus while strengthening transparency and informed consent,” Kennedy said in a statement.