https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6815659/pdf/jogh-09-020421.pdf
Comparing SARS-CoV2 to influenza A or B in terms of transmission, virulence, course of illness is unwise.
Comparing SARS-CoV2 to influenza A or B in terms of mortality and socioeconomic burden is reasonable IMO. I agree with WHO, CDC, and NIAID estimates that we will see far greater mortality with COVID-19 compared to any influenza strain we've seen in our lifetimes (I doubt anyone on CB lived through the Spanish Flu). However as we approach peak mortality in some countries, the global number will become more apparent, and is unlikely to be in the multiple millions.