说实在的，我们专业教育顾问很难有资格真正把这个医学问题回答清楚，不过我可以给您一个相对权威的参考如下，希望有帮助：
Did Covid vaccine get FDA approval?
The COVID-19 vaccines received emergency use authorization based on interim data that showed they were safe and effective for only about three months. For full approval, the FDA has at least six months of efficacy data to review -- and that means combing through and analyzing an enormous amount of information.
