I personally first saw it in this tweet translating the Welt article[0] and after looking into it other sources seem to agree.
For what is worth, in Germany's case, in particular, there is very little concern with them not sharing the vaccine, but I can see how the US might think it can profit by having exclusive rights to it initially..
0. https://twitter.com/nicktolhurst/status/1239117898901266432