It would likely be >1% mortality rate even with adequate healthcare. If it hit 40-70% of the population though, people would be basically on their own, so mortality rate would be 5-10%. Tens of millions of deaths.
Of course, this would never happen, since we as a society would enact major policies to slow the spread long before it got anywhere near that bad, just as Italy is doing for example. It just doesn't make any sense to wait for things to get worse to start enacting policies to slow its spread; if we're going to have to do it at some point, might as well do it early and reduce the spread.
Of course, this would never happen, since we as a society would enact major policies to slow the spread long before it got anywhere near that bad, just as Italy is doing for example. It just doesn't make any sense to wait for things to get worse to start enacting policies to slow its spread; if we're going to have to do it at some point, might as well do it early and reduce the spread.