On the order of Health Secretary Robert F. Kennedy Jr., the CDC has rewritten one of its plainest statements [1]. Where the page once said 'studies have shown there is no link between receiving vaccines and developing autism,' it now says that conclusion is 'not an evidence-based claim,' because studies 'have not ruled out the possibility that infant vaccines cause autism' [1].
That reverses the actual weight of the evidence. The no-link conclusion rests on some of the largest cohort studies ever conducted: a 2025 nationwide Danish study followed more than a million children and found no increased risk of autism or 49 other conditions from vaccine aluminum adjuvants, and a 2019 Danish study of over 650,000 children found no MMR-autism link even among those at high genetic risk [2].
The study Kennedy wants to run in their place - directly comparing vaccinated and unvaccinated children - is one researchers say cannot produce a valid answer [1]. Vaccinated children visit doctors more often, and so are diagnosed more often; a raw gap between the groups would measure how closely each is watched, not what causes autism [1]. A leading vaccine expert called the effort activism rather than science [1].
The timing is what makes the reclassification more than a semantic fight. The United States is in its worst measles year in decades: more than 2,100 confirmed cases so far, on pace to exceed 2025's 2,289 - the most in over thirty years - with 93 percent of cases in people who were unvaccinated or whose status is unknown [3].
National coverage for the measles vaccine has slipped to 92.5 percent, below the roughly 95 percent needed to keep the disease from spreading [3]. Telling parents that the safety of those shots is now an open question, at exactly this moment, is not a neutral act [1][3].
