Because unlike other situations whereas the Trump Administration hands out government money to its buddies like its candy — it apparently refused to hand out money for potentially life-saving vaccines. According to the Times, Pfizer actually approached the United States with at least 100m additional doses of the proposed COVID vaccine but was declined. Senior administration officials reportedly refused because there wasn’t an apparent FDA approval.
As a result of the inaction, the United States and American patients will have to wait until next year (particularly summer) for more doses of the vaccine. Summer is quite a ways away and right now the U.S is experiencing snowballing COVID cases like never before.