The autism-vaccine link theory goes back to before the turn of the century, when an infamous and ultimately retracted paper published in a prestigious medical journal made the claim. Its effect, however, has been long-lasting despite a concerted push by physicians to assure patients and parents of vaccines’ safety. U.S. states have seen a resurgence in preventable diseases like measles and whooping cough and led lawmakers to pass more stringent vaccine requirements. The rising number of autism diagnoses has the potential to exacerbate concerns about vaccines.

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But what does explain the rise? The CDC itself lays out a likely suspect: Under-diagnosis of the condition among certain populations—like black and Hispanic Americans—who are also regularly underrepresented in access to the health care system to begin with.

“Autism prevalence among black and Hispanic children is approaching that of white children,” explained Dr. Stuart Shapira, associate director for science at CDC’s National Center on Birth Defects and Developmental Disabilities, in a statement on the latest CDC figures. “The higher number of black and Hispanic children now being identified with autism could be due to more effective outreach in minority communities and increased efforts to have all children screened for autism so they can get the services they need.”

That’s right: Marginally improved access to, and better representation of, some groups may actually lead to an “increase” in autism rates and other diagnoses. But in a sense, it really just means that we’re getting a fuller picture of what the underlying numbers are to begin with.