The Flu shot is the most dangerous vaccine in the US based on settlement in compensations.
The last report issued in 2013 by the Department of Justice (Vaccine Court), for compensation made by the Health and Human Services for people injured or killed by vaccines, was released in December 2013, covering the period of 8/16/2013 through 11/15/2013. The report is available as a Power Point presentation here.
There were 139 claims settled during this time period, with 70 of them being compensated. So, just over 50% of the claims filed for vaccine damages were compensated during this period.