To what degree was it the lack of immunisation that lead to the Samoan deaths and to what degree the 'poor public health'? What percentage of those that contracted measles went on to die?
How percentage of the 1700 in NZ died? How many were even hospitalised? If zero or low, then given your Somoan comparison, might that not be an argument for good public health and not vaccination?
Where has there ever been a 95% of the entire population vaccination take up?
Even where immunisation rates have achieved 95%+ take up (of children; adults don't seem to figure as part of the herd...) there have still been outbreaks, so a good take up would not make the deaths "...entirely preventable...".
You say that it "...is likely..." that the outbreak originated in NZ, but then that NZ "...actually seeded..." it. Which one is it?