Not widely enough understood. Influenza is a segmented virus and generates new strains by reassorment. Where two different strains of influenza infecting a cell

Not widely enough understood. Influenza is a segmented virus and generates new strains by reassorment. Where two different strains of influenza infecting a cell shuffle their RNA segments to produce a third strain. Best to think of influenza as an ever shifting and recombining family of viruses. Covid19 has a single strand of RNA and doesn't do that.