The spread of the second wave of the new coronavirus (covid-19) is reported to be due to a mutation called D614G in the S-protein of SARS-CoV-2. It is said that the mutation of D614G increased the probability of open conformation of RBD for ACE2, boosting the infection rate.
https://www.cell.com/cell/fulltext/S0092-8674(20)31229-0
Although it seems that the novel coronavirus has now entered the third wave, there are reports that a mutation called A222V has been added to the NTD of the S-protein in this spread of infection. It is still unclear whether this mutation is a direct cause of the third wave of infection spread. In France, the percentage of strains that also contain mutations of S477N in the S-protein NTD is high compared to other European countries.
https://www.medrxiv.org/content/10.1101/2020.10.25.20219063v1