Study documents first case of coronavirus spread by a person showing no symptoms People showing no symptoms appear to be able to spread the novel coronavirus that has caused an outbreak in China and led world health authorities to declare a global emergency, researchers reported Thursday in the New England Journal of Medicine. If confirmed, the finding will make it much harder to contain the virus. The case described — from Germany — could help resolve one of the major unknowns about the virus, which as of Thursday night had infected nearly 9,700 people in China and killed 213. About 100 more infections have been reported in 18 other countries, but no deaths. Some viruses, including SARS, which is another coronavirus, can only be passed when a person is showing symptoms. Others, like the flu, can be spread a day or two before the onset of symptoms. If people are contagious before they become sick, they can be unknowingly spreading the virus as they go shopping or to work or to the movies. Trying to snuff out the virus in that case is a much more difficult task. What’s also concerning is that the spread from an asymptomatic person appeared to lead to two generations of cases, meaning the person who contracted the virus then passed it on to others. Support STAT: STAT is offering coverage of the coronavirus for free. Please consider a subscription to support our journalism. Start free trial today. The infection described in the new paper involved a woman from Shanghai who traveled to Germany for a business trip from Jan. 19 to Jan. 22 and displayed no signs of the disease, which include cough and fever. She only became sick on her flight back to China, and was confirmed on Jan. 26 to have the virus, known provisionally as 2019-nCoV. On Jan. 24, however, a 33-year-old German businessman who had had meetings with the woman on Jan. 20 and 21, developed a sore throat, chills, and muscle soreness, with a fever and cough arriving the following day. He began to feel better and returned to work Jan. 27. After the woman was found to have the virus back in China, disease detectives went to work, getting in touch with people who had been in touch with the woman — including the German businessman, who by then had recovered and appeared healthy during an examination in Munich. Tests, however, showed he had the virus. On Jan. 28, three coworkers of the businessman tested positive for the virus. Only one of these patients had contact with the woman from Shanghai; the other two only had contact with the German man. All four patients in Germany were isolated in hospitals and have not shown any signs of severe illness.