View attachment 12587
Image from COG consortium showing one aspect of variation in the virus. Position 501 is the amino acid residue number. The most common mutation is Y which is the code for Tyrosine. This is a hydrophobic amino acid because it has a benzene ring in its side chain. The original was a polar amino acid called asparagine. The switch from a polar to hydrophobic amino acid is likely to explain why this mutation affects the structure of the spike protein and hence why it evades 1/2 antibody neutralisation reactions. This is a guess.