From today's Guardian (they clain truth was not hurt during the making of this article)
What is the mortality rate of the new coronavirus?

It is probably about or a bit less than 1%. Much higher figures have been flying about, but the chief medical officer, Chris Whitty, is one of those who believes it will prove to be 1% or lower. The World Health Organization’s director general, Dr Tedros Adhanom Ghebreyesus, talked of 3.4%, but his figure was calculated by dividing the number of deaths by the number of officially confirmed cases. We know there are many more mild cases that do not get to hospital and are not being counted, which would bring the mortality rate significantly down.
Several things to note about the article.
The WHO mortality rate is rude crude and grossly exaggerates.
The common flu has a mortality rate of 0.1%( annual fatalities uk 17k)
Yesterday the UK figures quoted suggested that because 55 had died the number infected countrywide was 55000.
a 1% mortality = 550 deaths
a 0.1% mortality = 55 deaths.
It is a given that an old population and a polluted environment will skew the rate upwards, as will be the case when numbers start to swamp the system.
Assuming 80% eventually get infected that is 56 million so s death toll on those optimistic mortality rates is still 1/2 million deaths.
still early days so all numbers quoted are highly quesstionable.
The great flu pandemic death toll varies depending upon source. 2.5% - 10% mortality are quoted. But antibiotics to deal with bacterial pneumonia were not in the tool box back then, neither were ventilators or today's more advanced medical techniques.
In the early stages mortality rates are inevitably high calculations.
This is no bad thing as it forces government to look into the abyss and plan accordingly. The measures being taken now would have caused revolution a month ago.