Daily vaccination rates in the United States are dropping rapidly, making President Biden’s goal of having 70 percent of adults receive their first shot by July 4 increasingly unlikely. According to The Washington Post, the U.S. is now administering fewer than 1 million shots a day on average, a more than two-thirds decline from peak distribution rates of 3.4 million per day in April. The drop seems to coincide with the temporary suspension of the Johnson & Johnson vaccine after a number of rare blood-clot incidents were linked to its administration.

According to Dr. Anthony Fauci, part of the issue is that vaccines have already reached the “low-hanging fruit—those people who absolutely want to get vaccinated without telling you telling them anything,” and that the people who remain will need to be convinced. A number of states have begun to incentivize vaccinations with promotions and lotteries. The slowdown has been particularly felt in many Southern and Midwestern states. While daily COVID-19 case rates continue to decline in the U.S., experts say higher levels of immunization are required to prevent another surge next winter.