I remember that. I was paying attention. The Chinese set up field hospitals to deal with it. I thought later it was a psyop to scare the world about it to make the west overreact and destroy western economies, and if that was the plan it worked great. But China also suffered in locking down entire huge cities of many millions of people.
And then by the time it reached the USA it was largely a dud. Maybe it mutated shortly after being released. That's possible.