It depends on the cruise length, $50 for less than 7 days, $100 for 7 -14 days and $250 for those more than 14 days. It is in USD for cruises overseas and AUD for home cruises. Sometimes pounds for British cruises.
Some ports have weird rules for ship's services. While in Australian and most other ports, there is no shops, casino, etc. However in Greek ports, and a few other countries, they cannot sell drinks either, which means if you haven't got a package, you cannot get any drinks, or buy a package while docked.
I too had my 5th in July, would have been earlier but twice now I have had to wait due to having covid, once in April 2022 delaying my 4th shot and again in February this year delaying my 5th.
I do think they needed to keep pushing for people to maintain their vaccination, and therefore their protection.
And I do hope they have an annual flu and covid jab in the future.