But because the coronavirus spreads widely and quickly, it can overwhelm local health systems in a way that the flu does not. This is believed to be a driver of the high mortality rate in Wuhan, the region of China where it first spread. In other words, many of the people there who died after becoming infected might have survived if there had been sufficient health care workers and hospital beds to treat them. In South Korea, where government officials were more prepared (after all, they knew what was coming) and health care was more effectively administered, the mortality rate has been about 0.5 percent so far, a fraction of that in China — and it might even be lower.