Do you have an alternate, likely explanation why there is no higher incidence and was no flue season in Japan? I believe in testable hypotheses and reproducabl

Do you have an alternate, likely explanation why there is no higher incidence and was no flue season in Japan? I believe in testable hypotheses and reproducable experiments ... Yet that's a bit difficult when dealing with a pandemic and potentially deadly virus. It seems also from studies, that even cloth masks have an effect. If there's a chance I can save a life by the very slight annoyance of wearing a mask, isn't that something we should do?