Oh, sure that is so common that people are injecting themselves all over the world in public every hour of the day.
She isn’t going to keel over from scurvy on an airline flight for christsakes.
It is bizarre behavior, and poorly thought.
Although not uncommon in the circles of the wealthy insane.
Of course, there's also the comment of Claire MacEvilly: "Vitamin injections are an extreme and dangerous fad which has come from the US - it is not very popular over here yet and hopefully will not take off."
Those evil colonials! They are shooting up left and right! Nevermind the mention of Geri Halliwell in the story.
Perhaps it's the high-flying crowd, not by nationality. And there are very legitimate reasons for taking things intravenously.