We want progress in medicine to be clear and unequivocal, but of course it rarely is. Every new treatment has gaping unknowns - for both patients and society - and it can be hard to decide what do do about them.

If there is a credo in practical medicine, it is that the important thing is to be sensible.

The possibilities and probabilities are all we have to work with in medicine, though. What we are drawn to in this imperfect science, what we in fact covet in our way, is the alterable moment-the fragile but crystalline opportunity for one's know-how, ability, or just gut instinct to change the course of another's life for the better.

Are doctors who make mistakes villains? No, because then we all are.

The striking thing is that WHO doesn't really have the authority to do any of this. It can't tell governments what to do. It hires no vaccinators, distributes no vaccine. It is a small Geneva bureaucracy run by several hundred international delegates whose annual votes tell the organization what to do but not how to do it.…The only substantial resource that WHO has cultivated is information and expertise.

Expertise is the mantra of modern medicine.