The news that the Mississippi child said to be cured from HIV infection actually is not cured at all but rather is one of the 36 million people worldwide with the infection is altogether heartbreaking, despite the fact that the entire thing had always seemed fishy. At the time of the original announcement, I had expressed my doubts in The Daily Beast on two distinct occasions.

But something in me wanted to believe. After all, I have been thinking about and worrying about and dealing with people infected with HIV for my entire career and was around to witness the miracle of the 1990s when the protease inhibitors and other new, potent therapies transformed AIDS from a reliably fatal infection to a chronic disease. Since then, I have treated many people who have risen from near death and resumed their lives. I have seen infected women give birth to HIV-negative, totally healthy babies. I have talked to some longtime patients about their grandkids. I even have one patient who tells me about her great-grandkids. I have seen a lot I never imagined I would see.

So as the Mississippi story and its even-more-hyped echo, the California story, unfolded, I thought: why not? Maybe, maybe, maybe the treatment worked—maybe one kid out of millions got lucky. Medicine is nothing if not a series of unbelievable accidents and flukes, people who never should have survived but did, others who never should have died but did, and all the daily surprises in between. So why shouldn’t one child have some seemingly impossible confluence of one-in-a-million events that would lead to an extremely unlikely cure?

Seduced by hope, I had forgotten the rules of the world. Science allows for the unlikely, the extremely rare, the mind-boggling—but it does not allow for the impossible. Only Hollywood does that. And there is an enormous difference between extremely rare and impossible—just ask someone who has won lottery. There, an extremely rare event predictably does occur. But impossible events such as the sun rising in the west do not and cannot happen. Ditto medical cures of established HIV infection with the current generation of antivirals. Can’t happen—because science follows the rules of science, not hope.

So with the Mississippi news, I am left with continued grim respect for the biology of chronic viral infections and the iron-clad rules of science.