Answer:
Due to lack of cooperation.
Step-by-step explanation:
The goal can't be achieved due to non-serious behaviour of the people who are the followers of ex-President Donald Trump. If those people can cooperate and get vaccinated so the percentage will be higher than 70 or even 80. Due to lack of cooperation of people is the main reason for the decrease in the percentage of vaccinated people and fail to achieve the goal of 70 % vaccination of adult population.