The oncoming flu season has claimed its first lives, among them a child in Florida who had not gotten a flu shot.

This year’s vaccine significantly reduces the odds of getting sick — and you should get one now if you haven’t already — but it’s far from perfect.

For one thing, its effectiveness fluctuates from year to year. At best, the vaccine may reduce the risk of illness by about 60 percent. Last year, during one of the worst flu epidemics in recent memory, that figure was just 40 percent.

And if a new strain of the flu were to strike, it might take months to develop an effective vaccine — plenty of time for the virus to sweep the globe, claiming hundreds of thousands, perhaps millions, of lives.