The United States’ top infectious disease doctor said a new study published Thursday shows people can spread the Wuhan coronavirus before symptoms are exhibited, after people who showed no signs of sickness were diagnosed with the virus in five instances.
“There’s no doubt after reading this paper that asymptomatic transmission is occurring,” said Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, reported CNN. “This study lays the question to rest.”
A study published in the New England Journal of Medicine on Thursday night showed that four German business associates became infected through asymptomatic infection.
The coronavirus, first identified in Wuhan, China, has prompted lockdowns, travel bans, and quarantines across the city and other parts of Hubei province. The World Health Organization declared it a global health emergency while the U.S. State Department called on Americans to altogether avoid traveling to mainland China.
The study said a German businessman “had attended meetings with a Chinese business partner at his company near Munich on January 20 and 21. The business partner, a Shanghai resident, had visited Germany between Jan. 19 and 22. During her stay, she had been well with no signs or symptoms of infection but had become ill on her flight back to China, where she tested positive for [the Wuhan coronavirus]” on Jan. 26.
Dr. Camilla Rothe, an infectious disease specialist and the lead author of the paper, told CNN that the Shanghai woman hosted her parents, who came from Wuhan. They appeared healthy during their visit but were later diagnosed with the virus.
The Shanghai woman then left Shanghai and headed to Germany. She met with employees of a Munich company but still showed no signs of the virus’s symptoms. She became ill on the plane days later, Rothe said.
Two days later, according to Rothe, two German employees became sick. Rothe said one German worker was ill for a few days but recovered.
The other one had a “mildly sore throat and a minimal cough,” Rothe told CNN. “He was clinically unspectacular.”
Two more employees got sick about a week after the Shanghai woman infected the two German workers. Those employees didn’t attend the meetings with the Shanghai woman but spent time with the infected German employees before they had begun displaying symptoms, Rothe said. They both tested positive for coronavirus but were mildly ill, Rothe said.
“Despite these concerns, all four patients who were seen in Munich have had mild cases and were hospitalized primarily for public health purposes. Since hospital capacities are limited—in particular, given the concurrent peak of the influenza season in the northern hemisphere—research is needed to determine whether such patients can be treated with appropriate guidance and oversight outside the hospital,” according to the study.
The study comes after a top Chinese health official claimed that the virus could be transmitted without a patient exhibiting symptoms, although he provided no evidence.
Rothe’s revelation will likely prompt more stringent measures around the world in curbing the spread of the virus.
Meanwhile, the Centers for Disease Control identified the sixth patient in the United States, saying that a woman who had traveled from Wuhan transmitted the virus to her spouse in the first person-to-person case in the country.