China says the mystery virus that has sickened dozens of people in the central city of Wuhan is a new coronavirus in the same family as SARS, as experts said they don't believe official claims of no human-to-human transmission.
State news agency Xinhua quoted Xu Jianguo, the lead scientist on the team researching the virus, as saying that authorities had "preliminarily determined" that at least 15 patients in Wuhan had contracted the same virus.
The World Health Organization (WHO) confirmed the discovery.
"Further investigations are also required to determine the source, modes of transmission, extent of infection and countermeasures implemented," the WHO's China representative Gauden Galea said in a statement.
At least 59 people in Wuhan have been taken ill -- seven of them seriously -- with what was initially feared to be a resurgence of Severe Acute Respiratory Syndrome, or SARS.
SARS killed 349 people in mainland China and 299 in Hong Kong over the winter of 2002-2003.
Chinese health authorities had said the virus -- which first struck in Wuhan among employees of a now-shuttered seafood market -- wasn't SARS, and no human-to-human transmission has yet been reported.
But health experts have cast doubt on the claims about human-to-human transmission.
Ho Pak-leung, head of the University of Hong Kong's Centre for Infection, has warned that it is highly possible that the illness is spreading from human to human, given the sheer number of cases that have mushroomed in a short period of time.
Hong Kong authorities appear to be taking the possibility seriously, with health screening of all passengers coming into the city from mainland China already in place.
Infrared thermal screening
Incoming passengers from Wuhan are being given infrared thermal screening for signs of a raised temperature, while enhanced cleaning and disinfection measures are in place on Hong Kong's railway network and at the airport, secretary for food and health Sophia Chan told lawmakers on Wednesday.
Any inbound travelers with tell-tale symptoms who have been to Wuhan are being isolated and treated in government hospitals, Chan said.
Ren Ruihong, former head of the medical assistance department at the Chinese Red Cross, said she too has her doubts about the reported "absence" of human-to-human transmission in Wuhan.
"It's a new type of mutant coronavirus," Ren said. "They haven't made public the genetic sequence, because it is highly contagious. From what I can tell, the patients caught it from other people. I have thought that all along."
She said the lack of fatalities didn't indicate that the virus was less deadly than SARS, just that antiviral medications have improved in the past 10 years or so.
Ren said she also regarded the relatively high number of infections in Hong Kong with suspicion, given that there had been no reports of cases anywhere in between the two cities, in the southern province of Guangdong, for example.
"Genetic engineering technology has gotten to such a point now, and Wuhan is home to a viral research center that is under the aegis of the China Academy of Sciences, which is the highest level of research facility in China," she said.
Repeated calls to various numbers listed for the Wuhan Institute of Virology under the Chinese Academy of Sciences rang unanswered.
However, an employee who identified herself as a senior engineer said she knew nothing about the virus.
"Sorry, I ... I don't know about this," the employee said.
Lunar New Year travel looms
As of noon on Thursday local time, 10 patients -- five of whom are under seven years old -- had been admitted to hospital in Hong Kong with flu-like symptoms or pneumonia who had been to Wuhan during the past two weeks, Hong Kong's Hospital Authority said in a statement.
"The patients concerned had not visited [fresh food] markets in Wuhan before the onset of symptoms," the statement said.
WHO representative Galea said "people with symptoms of pneumonia and reported travel history to Wuhan have been identified at international airports," but no travel advisories have been issued for China as hundreds of millions get ready to travel across the country to spend Lunar New Year with their families on Jan. 25.
People living in Wuhan have said there is scant information in the media about the outbreak, in a country where media outlets are strictly controlled by the ruling Chinese Communist Party.
An employee who answered the phone at Wuhan's Jinyintan Hospital declined to comment when contacted by RFA on Thursday.
"We don't give interviews here," the employee said. "The only official channel for this matter is the Wuhan municipal health commission, so ... you can contact them directly to find out more."
However, calls to the Wuhan municipal health commission rang unanswered during office hours on Thursday.
Residents in the neighborhood around the Huanan Seafood Market, where the outbreak was traced to, said they knew very little about it.
"It's about 500 meters from here," one resident said. "We don't know anything about it, and I haven't been paying attention to it ... I don't think I went there recently."
SARS -- described as atypical pneumonia caused by a coronavirus -- infected more than 8,000 people around the world, and is believed to have originated in the southern Chinese province of Guangdong.
The WHO declared China free of the SARS virus in May 2004, although it criticized the Chinese government's initial attempt to cover up the crisis.
Reported by Wong Siu-san and Sing Man for RFA's Cantonese Service, and by Qiao Long for the Mandarin Service. Translated and edited by Luisetta Mudie.