curevac的失败和delta没关系。它失败的原因（总结自雪球网友阿企贴文）：1、三期临床中期分析数据表明对任何程度的病症保护效力都不足50%；2、采用的是未经化学修饰的mRNA，采用的是全长S蛋白，但剂量却比B和M两家低很多，Curevac三期临床使用的是12ug的剂量，而后两者使用的是30ug甚至100ug的剂量；3、curevac居然在1/2a期临床数据很一般的情况下，就贸然推动了大规模的2b/3期临床，招募了4万名志愿开展三期临床研究，这相当于跳过了2期临床，或者2、3期临床几乎同时开展。

以下为CUREvac官方解释：CVnCoV demonstrated an interim vaccine efficacy of 47%
against COVID-19 disease of any severity and did not meet prespecified statistical success criteria. Initial analyses suggest age and strain dependent efficacy. Available data were communicated with the European Medicines Agency (EMA). The Data Safety Monitoring against COVID-19 disease of any severity and did not meet prespecified statistical success criteria. Initial analyses suggest age and strain dependent efficacy. Available data were communicated with the European Medicines Agency (EMA). The Data Safety Monitoring Board (DSMB) confirmed a favorable safety profile for CVnCoV. The study is continuing to the final analysis and the totality of the data will be assessed for the most appropriate regulatory pathway.