The title above not only refers to the difference in convention of spelling adopted in British English as opposed to that adopted in American English.
I’ve just recently found out that here in the UK, not only are the recommended immunization schedules different from those in Japan, but there are also required vaccinations for diseases which are not required in Japan. I expected that there would some differences, of course, as conventions vary from country to country. It also depends largely on how old your child is.
However, I was surprised to know that in the UK immunization scheme, Aya is overdue for not just one, but several types of routine childhood vaccines necessary for living in the UK.