Two weeks ago, by inserting what must be the most notorious asterisk in modern public health, the Centers for Disease Control and Prevention caveated its long-standing position that vaccines do not cause autism. Under the direction of Robert F. Kennedy, Jr., the Secretary of Health and Human Services, a C.D.C. web page now contends that this is “not an evidence-based claim” and that research linking vaccines to autism has been “ignored by health authorities.” The fact that the original statement remains at all is due to an agreement with Senator Bill Cassidy, a physician and the chair of the Senate health committee, who disregarded decades of Kennedy’s vaccine skepticism to advance his confirmation after extracting a set of flimsy commitments that Kennedy is now betraying. The Autism Science Foundation said that it is “appalled” by the C.D.C.’s new stance; the American Medical Association warned of “dangerous consequences.”
The Department of Health and Human Services maintains that it is hewing to “gold standard, evidence-based science”—a piece of doublespeak so thick that it might unsettle Orwell. Discounting dozens of rigorous studies that have analyzed millions of patients and failed to connect vaccines to autism, the C.D.C. website claims that about half of parents of children with autism believe vaccines contributed to that autism. It cited a decades-old paper that surveyed a few dozen parents who strongly embraced alternative medicine, at two private practices in the Northeast. The web page points out that autism rates have risen in recent decades and so has the number of infant vaccinations—an observation that might also be made about prestige TV shows and pumpkin-spice lattes. The H.H.S. will now provide “appropriate funding” for studies on vaccines and autism, and last week it appointed a physician with a history of vaccine skepticism as the second-in-command at the C.D.C. The episode puts to rest any doubts about whether Americans can still trust information from the nation’s top health agency.
At stake is a question of the quality of information that should be taken seriously in public discourse and how that information should be communicated. Science may be the most powerful engine for grasping reality, but it suffers a rhetorical disadvantage. In science, the burden of proof falls on the one aiming to overturn the “null hypothesis”—the default position that one thing doesn’t cause another. But conspiratorial thinking is fuelled by the inverse: self-assured conjecture that demands a level of refutation no amount of evidence can offer. Proving the absence of a connection will always be harder than speculating about its existence. The language of science is measured and provisional; the language of politics is declarative and bombastic. In September, President Donald Trump told pregnant women to “fight like hell” not to take Tylenol, because of a potentially increased risk of autism in children; his Food and Drug Administration clarified that “a causal relationship has not been established and there are contrary studies in the scientific literature.” Tylenol, the agency wrote, remains “the safest over-the-counter” option for treating fever or pain.