Where are you going in Panama?
My family went to Panama for a very brief stay, so we were only in very touristy/developed areas (canal zone and the capital). Seriously, I'm a vaxer, but regardless of your status, I certainly wouldn't change my vaccination schedule at all for Panama. Other parts of Central and South America have factored in differently to our vax decision, but Panama was a non-issue because it's very much like the US in some areas of the country. (Incidentally, we were coming from a yellow-fever requiring country, but I did not get that vax for my daughter and we took our chances, but they let us into the country with no issue.) Even in rural areas, there have been no reported cases of measles, rubella, etc., and only 5 cases of tetanus for the entire country in 2008.