We have been told that we must have yellow fever vaccinations for a Panama Canal cruise. I checked each port and there were none that required this. We have cruised the canal before and yellow fever vaccination certificates were not even mentioned. Is this something new with HAL - or other cruise lines?
Here is the http://www.cdc.gov/travel/camerica.htm#vaccines link to the CDC Traveler's webpage for Central America and Mexico. [The generic CDC site is http://www.cdc.gov/travel; all travelers should bookmark this and use as a reference.] Part way down this page, you will find a link regarding Yellow Fever. Parts of Panama, are in the endemic Yellow Fever zone. Of course, I don't know how many people go into that zone while on a Panama Canal cruise.
Of course, the cruiseline can make a rule that you have a Yellow Fever shot or you don't cruise. This is regardless of what your doctor may say. Find out from your TA or HAL directly why they want the shot. If it is just because some of their shore excursions go into the endemic area, ask if you can avoid shot if you do not take those excursions.
We did not need to get Yellow Fever shot for either cruise to Panama. Of course, these were three and two years ago and the endemic zone may have changed.