In September I got my annual flu shot, or vaccine, along with this year's covid vaccine. I've had all the covid shots and boosters as they came along. Haven't had the flu or covid, although for the past week I've had my first common cold in years.

As for citations, there are many, but I don't feel like looking them all up for Streamer. Here's one from the New England Journal of Medicine that concluded 95% effectiveness:
https://www.nejm.org/doi/full/10.1056/NEJMoa2034577