(Or maybe it is just in the UK and US, I might be too myopic to see beyond that.)
Regarding Covid 19, I assume they meant the spread. Mutations happen all the time, but a human encroachment on nature means a cross-species transmission is more likely. Similar flare ups may have been common in the hunter-gatherer society, but a deadly outbreak would have wiped out one tribe and then die out. Nowadays, "one tribe" means the entire globe.