New data from the Centers for Disease Control and Prevention yesterday confirmed what experts have been warning: Fentanyl is not only deadly on its own, but is also contributing to other drugs' high death rates.

The big picture: As the nation's addiction crisis has unfolded, the No. 1 cause of overdose deaths has shifted from prescription drugs to heroin to fentanyl. And now cocaine — a stimulant, making it the odd man out — is also seeing a spike.

• Many overdose deaths involve more than 1 drug, and fentanyl crops up in a lot of those cases.

What they're saying: "Fentanyl overdose deaths, of course, keep going up. Cocaine overdose deaths [are] going up. The question we really have to get to the bottom of is: Is much of that [from] the lacing of cocaine with fentanyl? We certainly have seen some of that," HHS Secretary Alex Azar said at an Axios event yesterday.

By the numbers: While only about 1,600 overdose deaths were attributable to fentanyl in 2011 and 2012, this skyrocketed to more than 18,000 in 2016.

• About 40% of deaths attributed to cocaine overdoses also involved fentanyl, according to the CDC, as did 37% of heroin deaths and 19% of deadly oxycodone overdoses.

Related: Fentanyl is so potent (and so easy to smuggle into the U.S.) that now experts are worried about it as a potential weapon for terrorists, Bloomberg's Anna Edney reports.

• “Fentanyl-based drugs have been used in conflicts in other countries, so we know it’s possible," said Rick Bright, the director of the U.S. Biomedical Advanced Research and Development Authority.

Apple quietly employs dozens of doctors, "an indication that Apple is serious about helping customers manage disease, and not just wellness or fitness," CNBC's Christina Farr reports.

Why it matters: Apple has already begun to roll out a handful of health-related offerings — mainly its tool for electronic medical records and the new heart-monitoring capabilities on Apple Watch. But having a fuller staff of doctors on board (good ones!) signals bigger aspirations.

Between the lines: Employing doctors isn't just useful for managing directly health-related products, Farr notes.

• They can also help run the traps on new technologies, earning Apple more buy-in from the broader medical community as it rolls out new products. (Consider the educational resources and regulatory sign-offs that accompanied the latest Apple Watch.)

A reminder from Axios' Bob Herman: Next week, CVS Health and Aetna officials have to convince a federal judge in court that their closed merger is legitimate and that the settlement terms negotiated by the Department of Justice are fine and dandy.

Threat level: Judge Richard Leon, who gave the final seal of approval for the AT&T-Time Warner merger, likely can’t tell CVS and Aetna to unscramble their merger completely, said Andrea Agathoklis Murino, a former DOJ antitrust attorney now at the law firm Goodwin Procter. “But he can say the remedy was insufficient.”

• The deal’s main concession was Aetna agreeing to sell its Medicare drug plans to WellCare.
• However, that would mostly shift people toward another large player, and it wouldn’t address the antitrust concerns around stacking a health plan, a pharmacy benefit manager and pharmacies under one umbrella.
• It's a long shot to send everyone back to the drawing board, said Tim Greaney, a former DOJ antitrust attorney who teaches at UC Hastings. But that doesn’t mean the terms of the settlement can’t change.

An incoming member of Congress says he believes vaccines may cause autism, despite an overwhelming scientific consensus to the contrary.

Rep.-elect Mark Green, a Republican from Tennessee who is also a doctor, said he believes the CDC has "maybe fraudulently managed" data about the safety of vaccines. The Nashville Tennessean reported Green's remarks.

• "I have committed to people in my community ... to stand on the CDC’s desk and get the real data on vaccines. Because there is some concern that the rise in autism is the result of the preservatives that are in our vaccines," he said. "As a physician, I can make that argument and I can look at it academically and make the argument against the CDC, if they really want to engage me on it."

Reality check: The CDC has said unequivocally that vaccines do not cause autism, and any number of public health experts have reached the same findings. Failing or refusing to vaccinate children only allows otherwise preventible diseases to spread.