I had the Yellow fever shot last year, before we started flying to GRU and I did this in Doha.
The shot itself was free, I just had to pay like 10 QAR ( less than 3 USD ) to get the "passport" - a little orange booklet, in which they put an entry with a signature and a stamp to sertify I've got the jab. It's not Qatar Airways, it's a goverment Agency.
And Allianz was not even mentioned.
Cheers!