Sri Lanka, Vietnam, Thailand, Cambodia and Laos for example are doing extremely well, but Indonesia, Philippines, Malaysia and India not so. It doesn't seem likely that this can be wholly due to individual public health measures as the disparity is huge. Countries with well funded intensive public health measures such as Singapore, South Korea and Taiwan are also doing very well and here the success is understandable.
There is geographic cluster amongst those countries doing very well - is this a clue?
Could there be immunity in the population from exposure to a previous virus similar to SARS 2 eg SARS 1?