It is important to point out that Coronavirus emerged when the Northern hemisphere was still in Winter and early spring, a time where viruses can extremely thrive and now the Northern hemisphere is seeing a second wave because we still don’t have a vaccine and are entering a full new winter with COVID.
The southern hemisphere had only to battle COVID for a single Winter, and that delayed too, having had already the advantage of all the lessons learned in Europe. It’s very likely that their second Winter will already see a vaccine so by pure chance when the virus emerged countries in the Southern hemisphere have had a much better situation and therefore should expect better outcomes.