CDC makes no such distinctions in USA.
https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html
Any references to your claims?
Though I should have written "isn't _equally_ useful to everyone in the general population".
CDC makes no such distinctions in USA.
https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html
Any references to your claims?