Again, the very bad outcomes are fairly well known (deaths + hospitalizations) - it’s the # of non bad (mild and completely assymptomatic) outcomes they don’t know very well simply because most never are treated or tested
Of course, there are COVID-19 cases that have not been and never will be confirmed.
The CDC will probably estimate the number of COVID-19 cases and deaths later, just as it estimates the flu cases and deaths.
The actual number of confirmed deaths due to the flu is far, far lower than the CDC’s estimate.