claim: sars-cov-2 spike d614g variant confers enhanced replication and transmissibility
evidence_1: however, whether the increasing prevalence of the s-614g variant represents a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains elusive.", "here, we generated isogenic sars-cov-2 variants and demonstrate that the s-614g variant has (i) enhanced binding to human ace2, (ii) increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a novel human ace2 knock-in mouse model, and (iii) markedly increased replication and transmissibility in hamster and ferret models of sars-cov-2 infection.", 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  "collectively, our data show that while the s-614g substitution results in subtle increases in binding and replication in vitro , it provides a real competitive advantage in vivo , particularly during the transmission bottle neck, providing an explanation for the global predominance of s-614g variant among the sars-cov-2 viruses currently circulating.")