I paid 15 dollars retail for a flu shot today. The estimated actuarial price of a human life is approximately 10 million dollars. (http://en.wikipedia.org/wiki/Value_of_life)

So in principle flu shots like mine are "worth it" if it has a greater than 15 in 10 million chance of saving a life -- either mine or someone I might infect.

So, yes, for the price of a single life we could immunize about 600 thousand people. That's probably enough for herd immunity in an entire population for some region (like an entire state). Such a measure is bound to save more than one life.

By "everyone" I meant "in a company", and "losing" to mean "down for a whole week, at least". I should have worded that a lot better. My apologies.

If you're paying someone minimum wage, and they're a profit center for the company, their productivity over the week a flu would take them down is worth a lot more to you than a single flu shot. Extrapolate that to a whole department, which is likely to be lost because the flu is so contagious, and you're looking at a potential loss which is a lot more expensive than a department's worth of flu shots.