M58, is it true that flu vaccine makes flu to not to go full blown but it lingers on as sore throat for long time? Hope u get my point.

No. The flu vaccine either protects you completely from getting flu or lighten the severity of flu. The vaccine does not lead to a protracted course.
No. Flu vaccine significantly decreases the chance that anyone will get any symptoms related to the strains (3-4) within the specific vaccine. At any one time half a dozen strains may be circling the world and international air travel assures that a few uncovered strains will make it into your community.Not all flu can be prevented. Lots of rhinovirus and adenovirus masquerades as a flu.Get my point !