Are viral and bacterial illnesses really that much of a danger to humanity, as they once were during the time of the Spanish flu?

There was a panic about swine flu a decade ago, and now this Wuhan flu hilarity. Given the massive advancements in the availability of hygiene practices, fresh drinking water, access to good medical care, and vast distributed food networks, make it nearly impossible for a Spanish flu-like deathtoll to be reached again?

Or am I taking too much for granted, with regards to modernity?