The details of the procurement arrangements are not known to me, but in general, I think they are on these quarterly timelines. There are other factors at play, such as whether you have already domestic biomanufacturing on your soil, or a local candidate could be manufactured quickly using your own technology.
Evidence of meeting #18 for Industry, Science and Technology in the 43rd Parliament, 2nd Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was vaccines.
A recording is available from Parliament.