Scientists have long warned that a warming world is likely to hasten the spread of infectious diseases, making vaccination even more critical to safeguard public health.

And though most scientists hail vaccines as one of public health’s greatest achievements, they have provoked fear, distrust, and contentious resistance since Edward Jenner invented the first vaccine, to prevent smallpox, in the late 1700s.

Yet, until now, the United States never installed an outspoken vaccine critic like Robert F. Kennedy Jr. as a top health official with the power to upend federal childhood vaccine recommendations. Health and Human Services Secretary Kennedy and other top officials in the Trump administration have waged an “unprecedented attack on the nation’s evidence-based childhood immunization schedule,” a lawsuit, filed by 15 states, charged on Tuesday. Their actions will make people sicker and strain state resources, the suit claims.

A coalition of 14 attorneys general and Pennsylvania Governor Josh Shapiro, led by California Attorney General Rob Bonta and Arizona Attorney General Kris Mayes, is suing Kennedy, who has long promoted debunked theories linking vaccines to autism, as well as HHS, the Centers for Disease Control and Prevention, and its acting director, Jay Bhattacharya.

The multistate coalition is suing the agencies and their leaders, Mayes said in a press briefing Tuesday, “over their needlessly confusing, scientifically unsound, and unlawful revision of America’s immunization schedule.”

The suit also challenges Kennedy’s abrupt firing and “unlawful replacement” of 17 experts on the Advisory Committee on Immunization Practices (ACIP), which recommends which vaccines children and adults should receive, “with unqualified individuals whose minority anti-vaccine views align with Kennedy’s.”

In January, the CDC, with advice from the reconstituted ACIP, took seven childhood shots off the list of vaccines routinely recommended for all children, rescinding the CDC’s established guidance that vaccines protecting against rotavirus, meningococcal disease, hepatitis A, hepatitis B, influenza, COVID-19, and respiratory syncytial virus should be universally administered.