Inertia gets more obvious as the size increases in every case. Think about it, Europe with its small population had a much faster exposure and spread of covid as compared to India or Brazil. When India or Brazil picked up pace of spreading infection it just couldn’t be controlled. (Took Time and extra efforts to control). Inertia as such is proportional to size / character of a country (population, habits of people, economic factors etc).
What we have seen is lockdowns helping to curb the infection rate, vaccination drives helping to drive immunity and hence curb infection rate of any country. But we still see the infection rates raise and fall, this is because of the lack of standardisation. What we must try is all countries to have the same set of lockdown rules implemented at the same time. Then the world behaves as one country, one country which controlled the infection. When every country is anyway taking these measures why not try it together?