noun
flu shot; influenza vaccination
Refers specifically to the injection given to prevent influenza. The term 流感 is an older or more formal word for influenza, but the compound as a whole is still understood.
今年も流感の予防注射を受けた。
I got a flu shot again this year.
More common modern term for flu vaccination, using the loanword インフルエンザ and the broader term 予防接種 (vaccination).
Compound of 流感 (influenza) + の (possessive particle) + 予防注射 (preventive injection).