Wuhan Coronavirus Looks Increasingly Like a Pandemic, Experts Say

SARS killed about 10 percent of those who got it, and MERS now kills about one of three.The 1918 “Spanish flu” killed only about 2.5 percent of its victims — but because it infected so many people and medical care was much cruder then, 20 to 50 million died.By contrast, the highly transmissible H1N1 “swine flu” pandemic of 2009 killed about 285,000, fewer than seasonal flu normally does, and had a relatively low fatality rate, estimated at .02 percent.The mortality rate for known cases of the Wuhan coronavirus has been running about 2 percent, although that is likely to drop as more tests are done and more mild cases are found.It is “increasingly unlikely that the virus can be contained,” said Dr. Thomas R. That may make border-screening much harder, scientists said.Epidemiological modeling released Friday by the European Center for Disease Prevention and Control estimated that 75 percent of infected people reaching Europe from China would still be in the incubation periods upon arrival, and therefore not detected by airport screening, which looks for fevers, coughs and breathing difficulties.But if thermal cameras miss victims who are beyond incubation and actively infecting others, the real number of missed carriers may be higher than 75 percent.Still, asymptomatic carriers “are not normally major drivers of epidemics,” Dr. Fauci said. Nonetheless, there is some evidence that it works against coronaviruses, and Gilead has donated doses to China.Several American companies are working on a vaccine, using various combinations of their own funds, taxpayer money and foundation grants.Although modern gene-chemistry techniques have made it possible to build vaccine candidates within just days, medical ethics require that they then be carefully tested on animals and small numbers of healthy humans for safety and effectiveness.That aspect of the process cannot be sped up, because dangerous side effects may take time to appear and because human immune systems need time to produce the antibodies that show whether a vaccine is working.Whether or not what is being tried in China will be acceptable elsewhere will depend on how rigorously Chinese doctors run their clinical trials.“In God we trust,” Dr. Schaffner said.