Print this article Several southern states have fallen behind on vaccinations relative to the rest of the United States, and public health experts are pressuring states to meet the threshold of fully immunizing 40% of all adults. To date, more than 62% of U.S. adults over 18 have received at least one dose of a vaccine, while more than half of all adults have now been fully vaccinated, meaning that they have received both doses of the Pfizer or Moderna shots or the single-shot Johnson & Johnson vaccine. States in the northeast have administered the shots most expeditiously so far, with over 50% of all adults in Vermont, Massachusetts, Maine, Connecticut, and Rhode Island having been fully vaccinated.