Flu vaccines would be fine for everyone to take each year if the benefit exceeded the risk plus cost. The cost in a drug store to be vaccinated is about $25. No benefit can be demonstrated in those over 65 or in younger children, where 90% of flu deaths occur. (See several posts from earlier this week for more details.) In teens and healthy adults the vaccine probably stops some cases of flu. But the side effect below, although a known potential vaccine side effect, is not measured after flu vaccinations to see how common it is, despite its devastating effect.
Thus we have some evidence that flu vaccine causes an excess of 1-5 cases per million vaccinated, but we have no idea how many excess optic neuritis cases occur. Nor do we have rates for other illnesses caused by flu vaccine.
Binocul Vis Strabolog Q Simms Romano. 2012;27(3):171-3.