A friend of mine called my attention to Asian flu, which I lived through and remember, but hadn't thought about much. It also originated in China, and had a mortality rate of 0.67%, in the range of, very possibly greater than, estimates for C19. As is the case with C19, the elderly, and people with some other conditions, relating to the heart and lungs, were at greatest risk, but also pregnant women. The best estimate seems to be that it killed 116,000 Americans, though the number 70,000 is also thrown out. But keep in mind, the population of the country then was about half of what it is now.
Many of the things we're hearing now, such as concerns over the economy--the Dow Jones dropped 15%--were raised back then, but there were no lockdowns (though some businesses and schools were closed in the UK). One reason may have been because the symptoms were treatable to some extent with antibiotics (apparently, secondary bacterial infections were a major problem). Another reason, though, and I find this remarkable, is that a vaccine was quickly developed. Keep in mind that all the researchers have been saying it would take a year to a year and a half to develop a vaccine for C19, and even that would be far and away a record. A vaccine for Asian flu was developed--and this was back in 1957--within three months, and large-scale application of it began within five months. My best guess as to how this was possible is that at that time there weren't strict rules about how large and how long trials had to be. But it took a while for the vaccine to become available for everyone, with the result that a second, deadlier wave occurred in early 1958.
The virus responsible gradually weakened, but (some of its sequence, or genes) returned in another pandemic, the Hong Kong flu, in 1968, The mortality rate and total number of deaths from the HK flu were no worse than for the Asian flu, possibly because of some cross-immunity developed from survivors of the earlier flu. But it's generally considered the second worse pandemic of the 20th century, after the Spanish flu, with Asian flu third.