Flu shot, or not?

[jinx]

Also, has there ever been any bad re-actions / allergic reactions to the shot?

Well like you said, its a different shot every year, produced by a few different labs. There have been sanitation issues within the labs for the past few years, causing shortages - but I don't think you can say "the flu shot causes X" unless you're talking about one specific year/product.

Here's a wiki on the Swine Flu, which includes this info;

On February 5, 1976, an army recruit at Fort Dix said he felt tired and weak. He died the next day and four of his fellow soldiers were later hospitalized. Two weeks after his death, health officials announced that swine flu was the cause of death. Alarmed public-health officials decided that action must be taken to head off a major pandemic, and they urged that every person in the U.S. be vaccinated for the disease. President Gerald Ford was confronted with a potential swine flu pandemic. The vaccination program was plagued by delays and public relations problems, but about 24% of the population was vaccinated by the time the program was cancelled. [4]
An immunopathological reaction to the vaccine in some people is believed to have caused about 500 cases of Guillain-Barré syndrome resulting in death from severe pulmonary complications for 25 people. More people died from the vaccine than died from the swine flu itself.[4] Other influenza vaccines have not been clearly linked to Guillain-Barré syndrome.[5]