A group of Chinese experts this week isolated and obtained the genome sequence of the new virus, which is believed to be responsible for sickening dozens of people who visited a wild-animal market last month in Wuhan, in central China, state media reported Thursday.
The outbreak ahead of the Lunar New Year travel season in China has prompted health authorities across East Asia to increase screening of travelers for signs of fever, underscoring fears about its potential spread.
A Chinese preliminary assessment panel isolated the coronavirus — named for its crown-like appearance under a microscope — from samples taken from a single patient’s lung fluid, blood and throat swabs, the panel’s leader, Xu Jianguo, told the official Xinhua News Agency in an interview.
“The expert group believes that the pathogen of the unexplained cases of viral pneumonia has been preliminarily identified as a new type of coronavirus,” Xu said. “The virus was isolated from samples and showed a typical coronavirus appearance under an electron microscope.”
Developing specific drugs and vaccines against a new pathogen could take years, he said.
In a statement, the WHO said initial information about the Wuhan cases it obtained from Chinese authorities pointed to a coronavirus — a family of viruses that can cause the common cold, as well as SARS and MERS. There is no vaccine or treatment for SARS or MERS, which are epidemic threats.
“According to Chinese authorities, the virus in question can cause severe illness in some patients and does not transmit readily between people,” it said.
Coronaviruses cause illnesses of differing severity, the WHO said. Some transmit easily. Novel coronaviruses emerge periodically, with SARS emerging in southern China in 2002 and MERS a decade later.
SARS caused 774 deaths, while MERS, first reported in Saudi Arabia, has killed 851 people.
As surveillance improves, more coronaviruses are likely to be identified.
The WHO said more-comprehensive information is required to confirm the pathogen and to better understand the epidemiology of the outbreak, the clinical picture, the investigations to determine the source, how the illness is spread and the extent of infection.
In its statement Thursday, the WHO praised China for its efforts thus far. Public health experts have raised concerns about the lack of predictable and daily communication from Chinese leaders in charge of the response about what is known and remains unknown about the outbreak.
Chinese investigators conducted gene sequencing of the virus using an isolate from one positive patient sample. “Preliminary identification of a novel virus in a short period of time is a notable achievement and demonstrates China’s increased capacity to manage new outbreaks,” the WHO said.
China has “strong public health capacities and resources to respond and manage respiratory disease outbreaks,” the WHO said. In addition to treating the patients in care and isolating new cases as they are identified, the WHO said, Chinese public health officials “remain focused on continued contact tracing, conducting environmental assessments at the seafood market, and investigations to identify the pathogen causing the outbreak.”
The WHO also said it continues to monitor the situation closely and, together with its partners, is ready to provide technical support to China to investigate and respond to the outbreak.
Symptoms of the new Wuhan pneumonia include fever and invasive lesions on the lungs when viewed on chest radiographs.
The U.S. Centers for Disease Control and Prevention issued a health advisory Wednesday to clinicians about screening patients with severe respiratory symptoms for travel history to Wuhan.
Among the chief concerns about the outbreak is how readily this respiratory illness spreads from one person to another. So far, there have been no reports of infection among health-care workers treating patients or among family members who have not had the same exposure to the source, infectious-disease experts said.
“Then the level of concern is somewhat reduced, although it can always happen later and infections can change,” said Jeremy Farrar, director of the Wellcome Trust, a London-based global biomedical research charity.
“In Wuhan, there has not been a new confirmed case for around two weeks and the evidence does not suggest any human to human transmission,” he said in a statement. “Both of these are every reassuring for now.”
If the new virus is behaving like MERS, there could be some limited human-to-human transmission, which could explain why there have been clusters of cases in hospitals, said Andrew Rambaut, an infectious-diseases professor at the University of Edinburgh whose research focuses on the evolution of emerging viral pathogens in humans.
That could be from ill people in hospitals infecting one another, he said. Those cases would probably be severe infections.
When MERS hit Saudi Arabia, individuals were getting infected from camels. Many of the hospitalized cases were people with underlying health conditions, with many mild cases detected only using a test developed for the virus. The mild infections seem not to transmit to others, he said, “so they are dead-ends for the virus.”
As a result, MERS tends to cause small, self-limiting clusters of cases. MERS infections are still happening because people are still being exposed to infected camels, he said.
In China, authorities have not yet identified the source of the virus. It is almost certain to be a mammal, because coronaviruses are mainly mammalian viruses, Rambaut said.
Chinese authorities have closed the wild-animal market in Wuhan. If that is the source, the outbreak will probably go away, he said. But the virus will still be out there in the animals somewhere, so it is important to find the direct source.
Authorities also need to create a fast and sensitive test that can detect the new virus in clinical samples. “Once you know what you are looking for, it is much easier to find it,” Rambaut said.
Over the past week, people with symptoms of pneumonia and reported travel history to Wuhan have been identified at international airports. The WHO is not recommending any specific measures for travelers, and is advising against any restriction on travel or trade with China based on the information available.
China’s transport officials told reporters Thursday that they will take measures, such as disinfecting transportation hubs, to prevent the spread of the illness during the Lunar New Year period later this month, when more than 400 million Chinese are expected to travel.
Sun reported from Washington.