Thank you for the question.
Our vaccine contracts specify quarterly deliveries only, and the reason for that is—and I need to take you back to the month of August, early August, when we were concluding these contracts—that there was no sense of the timeline for the discovery of a vaccine. Indeed, in speaking with one of our suppliers this week, he said to me, “We didn't know when a vaccine would be produced, and as a result, we could only commit to quarterly deliveries at the time of contracting.”