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.
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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.