Not everybody is able to get the vaccine. That's why the vaccination goal isn't 100% of the population, it's 100% of the eligible population. Even that can't be achieved - as it's never been achieved with any other vaccine. That's all known and was anticipated. What wasn't anticipated was how low the vaccination rate would be and the leading indicator of whether the vaccination rate is high or low in a particular area is whether the majority of the voters are registered as Republicans or Democrats. No one saw that coming, yet here we are.