Dr. Jeffrey Klausner, adjunct professor of epidemiology at UCLA, said the idea the U.S. will have enough vaccine supply in six weeks to make every adult in the country eligible is “aspirational.”

“The delivery systems are there, but there’s just not enough supply,” Klausner told The Daily Beast. “In Southern California, we’ve had to close sites because there are not enough vaccines. We run sites that send people home everyday because we run out of supply.”

States like Rhode Island, Vermont, and New Hampshire are more likely to meet the May 1 deadline because of their small populations, and they have demonstrated consistent success in meeting vaccination goals. “For larger states like Florida, Texas and California, that’s not realistic,” Klausner said. “Those states will continue to prioritize by age, risk and zip codes. We also have to make sure that we are first reaching essential workers and populations that disproportionately suffered during the pandemic.”