When you say there's no mention on the Cunard website do you mean it says you don't need any vaccinations or you haven't found that section?
In "My Cunard" in the Before you sail section it says-
"Travel health advice
The health and well-being of our guests is important to us. Therefore we ask that you carefully read the following information prior to travel, and arrange any necessary vaccinations or medical care before your departure date.
Disclaimer: Since travel health advice, vaccination and malaria recommendations do change, you should check with your medical and insurance providers before departure and check My Cunard regularly.
Vaccine information
We recommend that all guests seek advice from their doctor or travel medicine clinic at least six weeks before their voyage, with regard to their personal travel plans to obtain appropriate advice, prophylactic medication and vaccinations prior to travel. Please check below for any mandatory requirements. You will find up-to-date travel information on the UK government funded website at www.travelhealthpro.org.uk"
This is the information for Panama from that site.
https://travelhealthpro.org.uk/country/174/panama