90,000 cases 3,000 deaths worldwide. That's over a 3% fatality rate.
But if you consider that most of those cases happened in the developing world, the demographics will have been skewed towards a younger age range so far.
Once covid-19 fully breaks in Europe and America, we're going to see a higher proportion of elderly people catching the virus and consequently a higher proportion of serious cases. That's obviously going to be balanced out by victims receiving a higher level of healthcare, but I still wouldn't be surprised if the fatality rate in the UK reaches around 4%.
If a quarter of the country catch it, that's potentially half a million deaths.
But that extrapolation is full of assumptions and very much the worst case scenario. Hopefully.