Three distinct ORF1a recombinants of the SARS-CoV-2 Delta variant of concern

The ongoing COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the emergency of various lineages through mutations and recombination. In the Delta lineage, we identified recombination events in the ORF1a gene, which divided the Delta sublineages into three different genotypes (Delta R1-R3). The regional distributions of Delta R1 and Delta R2 were not correlated, indicating that recombination occurred early in the Delta outbreak. The impact of the ORF1a gene on SARS-CoV-2 transmission remains unclear; however, our findings suggest that recombination may have contributed to the evolution and global spread of the Delta lineage.