A SARS-CoV-2 variant carrying the Spike protein amino acid change D614G has become the most prevalent form in the global pandemic. Dynamic tracking of variant frequencies revealed a recurrent pattern of G614 increase at multiple geographic levels: national, regional, and municipal. The shift occurred even in local epidemics where the original D614 form was well established prior to introduction of the G614 variant. The consistency of this pattern was highly statistically significant, suggesting that the G614 variant may have a fitness advantage. We found that the G614 variant grows to a higher titer as pseudotyped virions. In infected individuals, G614 is associated with lower RT-PCR cycle thresholds, suggestive of higher upper respiratory tract viral loads, but not with increased disease severity. These findings illuminate changes important for a mechanistic understanding of the virus and support continuing surveillance of Spike mutations to aid with development of immunological interventions.

携带刺突蛋白氨基酸变化 D614G 的 SARS-CoV-2 变体已成为全球大流行中最普遍的形式。对变异频率的动态跟踪揭示了 G614 在多个地理层面（国家、地区和市）的反复增加模式。这种转变甚至发生在当地流行病中，在引入 G614 变体之前，原始的 D614 形式已经很好地确立了。该模式的一致性具有高度统计显着性，表明 G614 变体可能具有适应性优势。我们发现 G614 变体作为假型病毒粒子生长到更高的滴度。在感染个体中，G614 与较低的 RT-PCR 循环阈值相关，表明上呼吸道病毒载量较高，但与疾病严重程度的增加无关。这些发现阐明了对于病毒机制理解很重要的变化，并支持对刺突突变的持续监测，以帮助开发免疫干预措施。