Earlier quoted context omitted.
The injected flu shot has completely inactivated (colloquially, dead) virus and cannot cause flu like symptoms. Recent formulation removed the egg allergy restrictions as well. There's effectively no reason for anyone to avoid being vaccinated.
My understanding has always been that since the dead virus works by triggering an immune response, 'symptoms' (that are actually part of the immune response, e.g. fever, soreness) can still occur, though they end quickly, as the body easily 'beats' the non-reproducing virus. Is this not the case? Regardless, a person with nothing to fear from the flu getting the shot anyhow and having a fever for a few hours sounds l…
The two key points:
1. "The most frequent reactions reported after vaccination in children and adults are pain and other injection-site reactions. Up to 64% of people vaccinated with IIV experience pain at the injection site, which usually resolves in 2. "Fever, malaise, myalgia, and other systemic symptoms that can occur after vaccination with IIV most often affect persons who have had no previous exposure to the influenza virus antigens in the vaccine (e.g., young children). In adults the rate of having these events is similar after IIV and after a placebo injection."
So other than your arm aching for <2 days where injected, the 'symptoms' are no more common than a placebo injection.