For English countries like Antigua and Barbuda or Saint Kitts and Nevis you only need to say to type Antigua or Saint Kitts. However for countries who uses a different language like Bosna i Hercegovina or Sao Tome e Principe you have to type the full name. All four examples are countries with names that contain the word "and" (or the Portuguese/Serbo-Croatian equivalent) so I feel like there should be some consistency between them.
I am not a native speaker of all these languages, so I am bound to make some mistakes, so if you don't point them out, I'll never find them.