Nigeria, May 22 -- On a cold January morning, somewhere above the Atlantic, a nurse quietly draws a vial of blood from the President of the United States. The world sees the speeches, the summits, but not this. Not the routine hum of machines tracking one man's every cell as if the planet depended on it. Because, in many ways, it does.

No one is more shielded, more tracked, or more medically monitored than the President of the United States. He is not merely a leader, he is an institution. A node in a global system whose health, both political and physical,can tip markets, shape diplomacy, and ripple across every time zone.

So when news broke that President Joseph R. Biden Jr. had been diagnosed with advanced prostate cancer, a stage wh...