@Todjaeger ...are flu vaccinations free in the US like they are in Canada? Any idea on the population % that bother to get vaccinated?
Okay, had a chance to look for answers to your questions. Per the CDC
here, the estimates are that of the US adult population the national average vaccination coverage for the 2018-2019 flu season (most recent available data) was 45.3%, with a per state average ranging from 33.9% up to 56.3%
The average numbers are a bit higher for children although eight of the states with the lowest flu vaccination rates for children also have had among the lowest rates for adults as well.
As for the cost of flu vaccinations in the US, that is a simple question with a complex and multi-part answer. The shortest and easiest way to put would just be to state, "it depends."
Now to really explain that I need to cover what the answer depends on. The first variable is the who and why of the vaccination. Next up would probably who/what healthcare coverage or insurance the person being vaccinated has. The last variable that I can recall right now which could make a difference is what flu vaccination is being administered, since there can be multiple flu vaccines available in a given flu season.
Now that first variable, the who and why, could be something fairly normal like getting vaccinated during a routine visit to one's doctor or pharmacy (a chemist for you lot over in the British Isles or Oz). In these cases, assuming the person has medical insurance coverage then the cost of the vaccination might be either free (paid for by the insurance) of there might be what is known as a co-pay which is usually a nominal amount of only USD$5 to USD$10 for vaccinations. As a side note, this potential co-pay could also be in addition to the 'normal' co-pay associated with seeing a doctor during a routine exam or follow-up visit. The specific details would depend on what the specific state laws require the medical insurance carrier to provide/cover, as well as who the insurance carrier is and what plan or level of coverage the person has.
However, sometimes local health departments will offer free flu vaccination clinics, often in conjunction with a local healthcare/hospital system and/or medical response organization like a MRC (Medical Reserve Corps) or DMAT (Disaster Medical Assistance Team) unit. There are a few potential different reasons why this could be done. Sometimes it is an attempt to 'stay ahead of the curve' if there seems to be a particularly nasty looking flu season or strain coming, other times it is done as part of a response exercise. After all, why just simulate running a medical POD (Point of Dispensation) drill to volunteer 'role-players' when something like a vaccination can be actually dispensed to the public which could help to mitigate the impact of a seasonal flu for some people?
Now that least question, regarding the potential cost depending on which vaccine is administered is likely going to depend on and be somewhat determined by both one's healthcare coverage, as well as who has access to specific flu vaccines, with some vaccines being recommended for certain populations more than others. I would recommend reading the
CDC page on flu vaccines as it provides a fairly concise but easy to understand explanation.