From the very early days of the Wuhan outbreak it was clear, and was the consensus of experts, that the virus was much more serious than a seasonal flu. There was indeed disagreement as to the best ways to combat it, but it was not said (by anyone credible that I saw) nor implied that the virus itself wasn't serious. I'm sure you could find an occasional counter-example, as there are going to be people in any field who are wrong about any given subject, but the consensus was pretty clear. (Note that I'm talking about actual experts, not politicians or pundits.)