Due to a looming cytokine storm in each host, time is most important. The Delta variant contains two deletions at positions 157 and 158.
’Based on a previously identified neutralizing monoclonal antibody escape mutant (Parker et al, 1998), we generated S4HVR160 and R161, which contained a 142 amino acid deletion in the HVR (hypervariable region).’
(MHV Neuropathogenesis: The Study of Chimeric S Genes and Mutations in the Hypervariable Region, in, The Nidoviruses [Kindle location 1340])
’Based on a previously identified neutralizing monoclonal antibody escape mutant (Parker et al, 1998), we generated S4HVR160 and R161, which contained a 142 amino acid deletion in the HVR (hypervariable region).’
(MHV Neuropathogenesis: The Study of Chimeric S Genes and Mutations in the Hypervariable Region, in, The Nidoviruses [Kindle location 1340])