Author claims "resulted in thousands if not millions of preventable deaths." but never elaborates on what these deaths were caused by in his view or what should

Author claims "resulted in thousands if not millions of preventable deaths." but never elaborates on what these deaths were caused by in his view or what should have been done differently. Also hindsight is 20/20. Since this was a novel situation, in hindsight we will always know what should've been differently, that doesn't mean it was wrong to take the measures that were taken at the time. But it doesn't seem that the author would care about things like that.