Something that isn't talked about, but is probably a big factor, is how soon they started taking action. Contract tracing is very effective, but its hard to "s

Something that isn't talked about, but is probably a big factor, is how soon they started taking action. Contract tracing is very effective, but its hard to "scale." The virus exponentially grows, so once the infection rate is higher than your capacity to contract trace, you've permanently lost the battle. Only really China, South Korea, and Australia have had substantial outbreaks that were later contained. But in each, the outbreak was geographically or socially relatively contained: Wuhan, Shincheonji Church, and Victoria.