We are on this year's holiday Amazon cruise as well. Our Primary Care Physician urged us to get the YF vaccinations along with Hepatitis A and a tetanus booster for me. In addition, he ordered oral prescriptions for malaria and typhoid for the two of us and an anti-diarrheal. And we're both in our mid-70's.
I felt a bit like a voodoo doll after we went in a week ago, but neither of us has had any side effects from all the jabbing.
Our YF vaccinations were US$300 each, the HepA's were $150 and my tetanus (TDAP) was $99, but we're very fortunate to have an excellent drug supplement program that told us to submit the invoices for reimbursement, which we've done.