When Covid was confirmed to be a form of SARS in January 2020 the only thing we had to compare it with was the first SARS in 2003, and to its cousin MERS in 2012.
SARS-1 killed nearly 9% of those who caught it. MERS killed 32%. No one knew whether SARS-2 would be as lethal as those two.
I sent some N95 masks to relatives. One of whom was a nurse during both the SARS1 and MERS thing and that was her specialty. She was very happy to have a “real” mask.