Coronavirus: Study claiming people can spread virus without showing symptoms is inaccurate, say experts
Health experts are still unsure whether people infected with coronavirus could pass on the infection to others without showing any symptoms.
The only well-documented evidence that makes the case for the asymptomatic spread is inaccurate, according to Robert Koch Institute (RKI), the German government's public health agency.
The evidence, published in the New England Journal of Medicine (NEJM), outlined the case of a Chinese woman who transferred the virus to two others in Germany despite not showing any signs of the disease.
China has claimed that people who showed no symptoms of the new coronavirus could spread the disease but the country provided no evidence to support that claim.
As scientists were mulling over such a possibility, NEJM published a report supporting China's claims. In it, scientists said that the woman in question visited Germany on January 20 and interacted with her colleagues. She tested positive on January 26. Two days later, two colleagues — with whom she had a business meeting — also tested positive.
"During her stay, she had been well with no sign or symptoms of infection but had become ill on her flight back to China," the authors wrote.
However, according to Robert Koch Institute, the woman displayed mild symptoms and was taking fever-suppressing medication during her stay in Germany. The German health experts added that the NEJM findings relied on recollections of her colleagues, instead of tracking down the woman and making their investigations.
To set the record straight, RKI has written a letter to NEJM, even though it was not involved in the paper, Science reported.
"I feel bad about how this went, but I don't think anybody is at fault here," virologist Christian Drosten of Charité University Hospital in Berlin, one of the authors of the study, told Science. "The woman could not be reached at first and people felt this had to be communicated quickly," he added.
Does it mean asymptomatic transmission doesn't occur?
Though the paper was flawed, experts think it is too early to write off the idea that people could spread the virus even without experiencing symptoms. Anthony Fauci, director of National Institute of Allergy and Infectious Diseases, is among them.
"This paper may or may not be flawed — it needs further investigation. But I don’t think it negates the concept," Dr Anthony Fauci, director of National Institute of Allergy and Infectious Diseases told The New York Times.
"This evening I telephoned one of my colleagues in China who is a highly respected infectious disease scientist and health official. He said that he is convinced that there is an asymptomatic infection and that some asymptomatic people are transmitting infection," Fauci told Science.
If this were true, isolating suspected patients — which earlier helped quell the SARS outbreak — would turn out to be ineffective and thus controlling the virus spread could get harder, fear experts.
But according to the World Health Organization's February 1 situation report, this mode of infection may be rare. People are more likely to contract the infection through coughing and sneezing, they say. So far, 27 cases of the person-to-person spread of the virus have been documented in nine countries outside of China, WHO officials said.
Scientists will need to gather more data to be sure of asymptomatic mode of transfer. "More data may come out soon. We will just have to wait," Marc Lipsitch, an epidemiologist at the Harvard TH Chan School of Public Health said.