Although personally I wouldn't have the flu vaccine, the fact that it exists is a testimony to the efficacy of modern medicine. Those who are against immunisations as a whole might like to imagine life before routine vaccination was brought in.
My grandmother and her two sisters had diphtheria in the 1940s. Diphtheria causes a membrane to grow either across the nose or throat - if you're unlucky enough to have both grown over, you die. Or at least you did then. It's contagious. They were treated in an isolation hospital a long way from where their parents lived. When their parents visited, they had to view them through glass and weren't allowed to touch or speak to them. Any presents brought in were burnt once the girls were better again, as was all their bedding and clothes. They were in hospital for SIX months, a huge chunk out of their lives at the time.
Although medicine has come on in leaps and bounds since then, diphtheria can and does still kill children and adults. In the 90s, there was a huge outbreak in the former USSR after the vaccine programme broke down, killing 5000 people. I'm sure my great grandmother would have given anything to prevent her children becoming so very sick, especially something so small as a quick injection.
Vaccinations are not some evil plague wrought by pharmaceutical companies to kill us all and then take our money. They have improved life expectancy among children IMMEASURABLY in the last 60 years, and eradicated some previously widespread infections, such as smallpox.