By the numbers: Around 106 million Americans are already fully vaccinated, and 148 million have received at least one dose, per the CDC. Slightly more than 56% of adults have gotten at least one dose of the vaccine, meaning 14% more of the adult population has to get a shot before July 4 to reach the president's goal. Context: Biden's previous vaccination goals — 100 million doses in his first 100 days, which he then upped to 200 million — were relatively easy to meet. This one is "going to be harder because the next group of people who need to get vaccinated are just much harder to reach. They're either far more ambivalent about getting vaccinated or have lots and lots of questions," said Ashish Jha, dean of Brown University School of Public Health.