The US nationalized production in that government decree made it illegal to ship to anyone else unless US contracts had been satisfied in full (NOTE: I am not judging this at all. The merits of it are arguable, but it does point out a weakness in a reliance on free trade). The change of government didn't change this an iota.
The defense production act dictated that 100% of production was for the US until the government said otherwise. Moderna and Pfizer were both forced to supply Canada from the European factories as a result, even long after US vaccine manufacturing far exceeded consumption.