This is what occurred with Covid. While increasingly virulent strains pelted away at our border controls, we lapsed into bare-faced oblivion of the risks around us.
The number of scans of the Covid tracer app on January 17 was 485,620. News that Covid-positive cases were afoot among us shook the complacent and by Tuesday, January 26, there were more than a million - 1,067,641 - scans.
But such figures only tell one part of the story. The real picture was one of masks left discarded on dressers; hands left unwashed; people gathering in increasingly large numbers within increasingly confined spaces.
The figures which should have jolted us into vigilance - such as the UK passing 100,000 coronavirus-related deaths and the world officially surpassing 100 million cases of Covid-19 - faded into the background of Facebook memes of Bernie Sanders being superimposed on popular rock album covers.
Covid loves complacency, it's the very thing it relies on to continue to exist. Do not be lulled, the virus isn't.