There's a wide range of measures that lead to effectively no infection. You have no way of knowing that the "correct" measures were taken, only that measures at least as expensive as necessary were taken. They could well be far more expensive than necessary.
That's the future-history perspective, too, where we assume that we can already count them as having successfully contained the disease; in the here-and-now perspective, there's plenty of time for it to develop that they in fact didn't do enough either and will explode in disease in the next two weeks or something. Or months. Or, in the worst scenario, years. (See Spanish Flu history, as you've probably seen cited; what we know of as the "Spanish Flu" was not the original outbreak, but a later one.)
That's the future-history perspective, too, where we assume that we can already count them as having successfully contained the disease; in the here-and-now perspective, there's plenty of time for it to develop that they in fact didn't do enough either and will explode in disease in the next two weeks or something. Or months. Or, in the worst scenario, years. (See Spanish Flu history, as you've probably seen cited; what we know of as the "Spanish Flu" was not the original outbreak, but a later one.)