We found four striking differences in the COVID-19 case fatality rate (CFR). All of these striking differences suggest that, besides vaccination, good isolation of cases, disinfection of their living environments, and maintenance treatment (IDM) are highly effective is in mitigating COVID-19. This suggestion is crucial to the global control of the pandemic and consistent with the theoretical functions of IDM in minimizing co-infections with various other pathogens and maintaining human body functions. Accordingly, the risk for China to move away from its zero-COVID policy shall depend on China’s control measures. The CFR of COVID-19 in China can remain less than one tenth of that of influenza, namely that COVID-19 can remain “tiny influenza” in China, if the IDM measures are well implemented (e.g., staying at well-disinfected home with good rest for vast mild cases). Otherwise, the CFR of COVID-19 in China can be several times higher than that of influenza, namely that COVID-19 can be “giant influenza” in China. This analysis also clarifies that the COVID-19 CFR shall increase greatly if many asymptomatic or mild COVD cases are isolated together at temporary hospitals.