Maybe you should do some research that is backing his decision. I certainly wouldn't be getting a flew shot, nor my family. Most people who get the flew shot (last year's strain) get the flew.
I get the flu shot every year , have been doing so since I was in my mid 30’s and following my diagnosis as an Asthmatic.
I’ve never got sick once after a flu shot.
But I respect your position and not having a go at you just stating it’s never once affected me like that.