Blaming supply constraints is a great cover for these organizational and regulatory failings, though. "We don't have enough vaccine" sure sounds better than "we've only bothered to use 60% of the vaccine we got our hands on" (hello, Rhode Island and D.C.).
It's complicated. Right now there are vaccines that have been purchased and produced but not delivered due to regulatory approval issues (70 million from just one manufacturer, according to https://www.theguardian.com/global-development/2021/feb/14/w... ), vaccines being delivered but not used (see https://www.bloomberg.com/graphics/covid-vaccine-tracker-glo... "Supply used" statistics), and so forth.
Blaming supply constraints is a great cover for these organizational and regulatory failings, though. "We don't have enough vaccine" sure sounds better than "we've only bothered to use 60% of the vaccine we got our hands on" (hello, Rhode Island and D.C.).