The B.1.617.2 (Delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in the state of Maharashtra in late 2020 and spread throughout India, outcompeting pre-existing lineages including B.1.617.1 (Kappa) and B.1.1.7 (Alpha)¹. In vitro, B.1.617.2 is sixfold less sensitive to serum neutralizing antibodies from recovered individuals, and eightfold less sensitive to vaccine-elicited antibodies, compared with wild-type Wuhan-1 bearing D614G. Serum neutralizing titres against B.1.617.2 were lower in ChAdOx1 vaccinees than in BNT162b2 vaccinees. B.1.617.2 spike pseudotyped viruses exhibited compromised sensitivity to monoclonal antibodies to the receptor-binding domain and the amino-terminal domain. B.1.617.2 demonstrated higher replication efficiency than B.1.1.7 in both airway organoid and human airway epithelial systems, associated with B.1.617.2 spike being in a predominantly cleaved state compared with B.1.1.7 spike. The B.1.617.2 spike protein was able to mediate highly efficient syncytium formation that was less sensitive to inhibition by neutralizing antibody, compared with that of wild-type spike. We also observed that B.1.617.2 had higher replication and spike-mediated entry than B.1.617.1, potentially explaining the B.1.617.2 dominance. In an analysis of more than 130 SARS-CoV-2-infected health care workers across three centres in India during a period of mixed lineage circulation, we observed reduced ChAdOx1 vaccine effectiveness against B.1.617.2 relative to non-B.1.617.2, with the caveat of possible residual confounding. Compromised vaccine efficacy against the highly fit and immune-evasive B.1.617.2 Delta variant warrants continued infection control measures in the post-vaccination era.

严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 的 B.1.617.2 (Delta) 变种于 2020 年底在马哈拉施特拉邦首次被发现，并在印度各地传播，击败了包括 B.1.617 在内的现有谱系。 1 (Kappa) 和 B.1.1.7 (Alpha) ¹ . 在体外，与携带 D614G 的野生型 Wuuhan-1 相比，B.1.617.2 对康复个体的血清中和抗体的敏感性低六倍，对疫苗引发的抗体的敏感性低八倍。ChAdOx1 疫苗接种者中针对 B.1.617.2 的血清中和滴度低于 BNT162b2 疫苗接种者。B.1.617.2刺突假型病毒表现出对受体结合结构域和氨基末端结构域的单克隆抗体的敏感性降低。在气道类器官和人气道上皮系统中，B.1.617.2 表现出比 B.1.1.7 更高的复制效率，这与与 B.1.1.7 尖峰相比，B.1.617.2 尖峰处于主要裂解状态有关。与野生型刺突蛋白相比，B.1.617.2刺突蛋白能够介导高效合胞体形成，其对中和抗体的抑制不太敏感。我们还观察到，B.1.617.2 比 B.1.617.1 具有更高的复制和尖峰介导的进入，这可能解释了 B.1.617.2 的优势。在混合谱系循环期间对印度三个中心的 130 多名感染 SARS-CoV-2 的医护人员进行的分析中，我们观察到相对于非 B.1.617，ChAdOx1 疫苗针对 B.1.617.2 的有效性降低。 2、注意可能存在残余混杂因素。针对高度适合和免疫逃避的 B.1.617.2 Delta 变体的疫苗功效受损，需要在疫苗接种后时代继续采取感染控制措施。