Bees need rest just like any other living thing. Without rest bodies are prone to disease and infection which can cause serious illness. The effect would be the bees would be less efficient in doing their pollination.
I just did it on edg and this was the answer they gave
Explanation: For vaccine to be delivered in time for vaccination to begin in the fall, manufacturers may begin to grow one or more of the vaccine viruses in January based on their best guess as to what viruses are most likely to be included in the vaccine.