Americans make up 4.4% of the world's population.  So if we simply extrapolate these numbers to the rest of the world -- now we're getting into really fuzzy estimates, so the margin of error is pretty great here -- this gives us 90 million deaths globally from COVID-19.  That's 15 Holocausts.  That's 1.5 times as many people as died in World War II, over 12 years.  This would take 3-6 months.