> Got my flu shot last year, still ended up with severe flu in February. The flu shot is not completely effective. My understanding is that the 'flu shot' cha

> Got my flu shot last year, still ended up with severe flu in February. The flu shot is not completely effective. My understanding is that the 'flu shot' changes every year, in anticipation of the strains predicted to be the most prevalent that year. In other words, flu shot producers say "we think flu strains A, B, and C will spread this year" and strains B, C, and D may be what actually spread. It's still worth getting because even if you catch strain D, your immune system still easily defeated B and C when exposed and you didn't even notice.