Earlier quoted context omitted.
That's a 0.4/8.9 reduction, about 5%. However, flu vaccine isn't useful to the general population. In many countries is usually administered to people that are most likely to develop complications such as pulmonitis.
> However, flu vaccine isn't useful to 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?
Though I should have written "isn't _equally_ useful to everyone in the general population".