Starting in November 2002, SARS a virus related to COVID-19 started to spread in China. It was transmissible as COVID and was much more deadly. COVID has a case fatality rate of just over 1.2 percent.
In comparison SARS infected roughly 10,000 people and had a 10 percent case fatality rate.
The WHO moved into China immediately and the transmission was limited as the borders were locked down almost immediately. They had the ability and knowledge to stop COVID, but politics got in the way.