US surpasses 700,000 coronavirus cases; toll tops 36,000

Feb 22: A 20-year-old Chinese woman from Wuhan, the epicentre of the coronavirus outbreak, travelled 400 miles(675 km) north to Anyang where she infected five relatives, without ever showing signs of infection, Chinese scientists reported on Friday, offering new evidence that the virus can be spread asymptomatically.

The case study, published in the Journal of the American Medical Association, offered clues about how the coronavirus is spreading, and suggested why it may be difficult to stop.

"Scientists have been asking if you can have this infection and not be ill? The answer is apparently, yes," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, who was not involved in the study.

China has reported a total of 75,567 cases of the virus known as COVID-19 to the World Health Organization (WHO) including 2,239 deaths, and the virus has already spread to 26 countries and territories outside of mainland China.

Researchers have reported sporadic accounts of individuals without any symptoms spreading the virus. What's different in this study is that it offers a natural lab experiment of sorts, Schaffner said.

"You had this patient from Wuhan where the virus is, travelling to where the virus wasn't. She remained asymptomatic and infected a bunch of family members and you had a group of physicians who immediately seized on the moment and tested everyone."

According to the report by Dr Meiyun Wang of the People's Hospital of Zhengzhou University and colleagues, the woman travelled from Wuhan to Anyang on Jan. 10 and visited several relatives. When they started getting sick, doctors isolated the woman and tested her for coronavirus. Initially, the young woman tested negative for the virus, but a follow-up test was positive.

All five of her relatives developed COVID-19 pneumonia, but as of Feb. 11, the young woman still had not developed any symptoms, her chest CT remained normal and she had no fever, stomach or respiratory symptoms, such as cough or sore throat.

Scientists in the study said if the findings are replicated, "the prevention of COVID-19 infection could prove challenging."

Key questions now, Schaffner said, are how often does this kind of transmission occur and when during the asymptomatic period does a person test positive for the virus.

The head of the World Health Organisation on Tuesday warned the novel coronavirus was a "very grave threat" for the world as he opened a conference to combat the epidemic.

"With 99% of cases in China, this remains very much an emergency for that country, but one that holds a very grave threat for the rest of the world," Tedros Adhanom Ghebreyesus said in Geneva.

Some 400 scientists will review how the virus is transmitted and possible vaccines at the two-day forum.

"What matters most is stopping the outbreak and saving lives. With your support, that's what we can do together," Tedros said.

The virus, first identified in China on December 31, has killed more than 1,000 people, infected over 42,000 and reached some 25 countries.

Participants will also discuss the source of the virus, which is thought to have originated in bats and reached humans via another animal such as snakes or pangolins.

There is no specific treatment or vaccine against the virus, which can cause respiratory failure.

Tedros, who has repeatedly urged countries affected to share their data, called for global "solidarity".

"That is especially true in relation to the sharing of samples and sequences. To defeat this outbreak, we need open and equitable sharing, according to the principles of fairness and equity," he said.

"We hope that one of the outcomes of this meeting will be an agreed roadmap for research around which researchers and donors will align," Tedros said.

Several companies and institutes in Australia, China, France, Germany and the United States are racing to develop a vaccine -- a process that normally takes years.

Asked whether scientists from Taiwan would be allowed to take part in this week's Geneva conference, WHO officials said that they would do so but only online -- along with colleagues from other parts of China.

While the WHO does not deal with Taiwan directly and only recognises Beijing, Taiwan was often allowed to attend annual assemblies and sideline meetings as an observer.

But in recent years it has been frozen out as Beijing takes an increasingly combative stance towards democratic Taiwan, which it considers its own territory.