By the time US public health agencies woke up to the severity of the situation in the middle of December, there had already been 40 million people vaccinated, and there had been 67 reported cases of patients dying due to adverse reactions. Many people also found that the vaccine had bad effects on their nervous systems: Some felt sapped of energy and others found it difficult to swallow.
12 月中旬，當美國公衛單位驚覺情況失控，下令停止注射時，已經有 4,000 萬名民眾施打了疫苗，其中疑似造成 67 起死亡案例，另有不少民眾出現手腳無力、吞嚥困難等神經病變。