I was not aware of a second anything here. I got a shingles shot ($15 copay through retiree medical) a few years ago. When did this Shingrix come out. This new, news is a shocker to me.
Shingrix was approved in late 2017.
According to the trials, it is 97% effective at age 50, and - from memory - it is still 90% effective at age 80.
With results like that, there was a huge surge of demand for the vaccine in the USA, and there has been a Shingrix shortage since mid-2018.
The un-insured cost for one shot of Zostavax, which is what I presume you got, was down to about $250 in 2017.
Shingrix requires two shots, and it's twice as good, so I will not be surprised if it costs $500 or more for an un-insured person.