The flu shot is modestly effective at preventing or reducing the health consequences of getting the flu. Most people handle it with hardly any adverse effects. A small number of people will absolutely have significant adverse or life threatening effects each year, but the shot is much more effective than it is dangerous in the average person. If you are someone who has had a bad response to the flu shot, you should definitely not get another one. But it is a bad idea to make general recommendations about the flu shot based on the experience of a small handful of people.

All medical therapies hurt someone, somewhere down the line. If we based all our treatment choices on whether anyone ever had an adverse reaction to a therapy, nobody would ever be treated for anything.