We had to get the shot when we went to Manaus, Brazil on the Amazon River and also the visa. Unless you go into the interior parts of Brazil, Peru and maybe other countries, you will not need the shot. They are very expensive and where we live you can only get them in 2 of our Hospitals. They are given only twice a month. If you are just taking the cruise you will not need the shot. I looked at your cruise and couln't see why anyone would say that a shot would be needed. We are booked out of Buenos Aires in Feb. and will end up in Chile and again no shot is needed. Hope that this helps.