Heinsberg study suggests a mortality rate of about 0.36%. This is high, but not "a big threat". Given that with 0.36% and 15% infection spread in the general population (like flu) you look at ca 162k deaths in the US.
It is not even close 5.7% mortality. If it would be that lethal you would look already at over one million deaths.
It is extremely irresponsible to say this is not a big threat. At this rate, the death toll of Covid19 in the US is up to as big as 4 times the seasonal flu. In some countries the mortality will end up being more than 0.8%. Almost 1 in every 100 people dying because of a virus seems like a big threat to me, and it is already clear that this will be way bigger than the Swine Flu.
That's not exactly what the article is saying tho. Also it doesn't change the 0.36% mortality rate and I might add the high age median of around 80. So we will likely see a lower average mortality afterwards.
It is not even close 5.7% mortality. If it would be that lethal you would look already at over one million deaths.
Sweden is a good example of a country without a lot of counter measures and we see that it will end in the realm of 0.36% lethality (5,4k deaths). https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Sweden