The Spanish Flu was almost exactly 100 years ago. Recent enough that we think of it as being in modern times with relatively modern medicine and hospitals. My grandmother lived through it, so this isn't the distant past.

Current estimates are that it killed up to 100,000,000 million people, as many as the black plague.

We have much better medicine now, thankfully. But we also live in a much more deeply connected world with millions of people flying every single day.