Full vaccination. A few countries (developed countries with high levels of vaccine acceptance) will be able to vaccinate virtually everyone over 16 within the next month or so, maybe everyone over 12 (though there is likely to be way more hesitancy there almost everywhere). At that point, it's likely to be suppressed in those countries, and that may reduce hesitancy elsewhere, and so on.
A number of diseases that were once globally endemic are now regionally endemic (eg polio, two countries), or eradicated (smallpox). Generally due to vaccination.