You're correct. See [1]. It's usually less than 50% effective, and as low as 19%. A troubling fact is that effectiveness has been on a downward trend the las

You're correct. See [1]. It's usually less than 50% effective, and as low as 19%. A troubling fact is that effectiveness has been on a downward trend the last 4 years. [1] https://www.cdc.gov/flu/vaccines-work/effectiveness-studies.htm https://www.cdc.gov/flu/vaccines-work/effectiveness-studies....