The risk of not getting the vaccine is about five days of agony and time off work, plus medication costs.
In the UK the converse is true- most people don't get the flu vaccine because you have to pay for it, and if you get ill, you just go get free treatment.
That seems backwards. Wouldn't making the vaccine "free" be more cost effective over all?
No, prevention is often more costly because you pay for EVERYONE. You treat only those who get sick (a much smaller number, unless there is an epidemic).
I would have thought the vaccine cost was significantly lower than the treatment cost.
Per person, yes. But you can still have this effect overall:
Example (not based on flu numbers -- I have no idea what they are): vaccine (100% effective): cost $10 per person.
treatment for disease (100% effective): $10,000 per person.
If no one gets vaccinated, 10,000 get sick. Population 50,000,000
Cost of vaccination: $500,000,000.
Cost of treatment: $100,000,000.
Letting people get sick is cheaper.