On the contrary, consider Ralph Steinem [0], who was awarded the Medicine prize in 2011, three days after his death. The news had not yet reached the prize committee. There are a couple others[1,2] from decades past that were nominated before their death, and the committee selected them after their death, but that loophole was closed in 1974.

As I said, edge cases.

[0] https://en.wikipedia.org/wiki/Ralph_M._Steinman

[1] https://en.wikipedia.org/wiki/Erik_Axel_Karlfeldt [2] https://en.wikipedia.org/wiki/Dag_Hammarskjold