This is true, however, vaccine manufacture is incredibly complex - especially for a novel one, and one that had to be stored at such a low temperature. And that complexity translates into incredibly time and expenditure to establish new manufacturing facilities - how did they have time to set up the plants AND after the huge lead time to establish the plants it still would have taken time to manufacture 24 billion doses - the only way it could have been done is if you had foreknowledge and you had the plants ready and already set-up and all you had to do is flick the production switch.