The coronavirus, “causes more severe illness than flu, there are not yet any vaccines or therapeutics, and it can be contained — which is why we must do everything we can to contain it.”Another difference: Covid-19 generally seems to lead to more severe disease than seasonal flu strains, in part because people have no immune protection against the new virus . Flu infections generally kill “far fewer than 1% of those infected,” Tedros said, but as of now, about 3.4% of Covid-19 cases have been fatal. (The fatality rate for Covid-19 is considered preliminary, especially given that experts are not sure how many mild cases are going undetected by health systems.)