The 2019 novel coronavirus (2019-nCoV) appears to have symptoms similar to those of severe acute respiratory syndrome (SARS) and may be capable of spreading from person to person and between cities, according to two studies published in The Lancet journal.
These early but important findings involve only a small number of patients, the researchers said.
They stress the need to maximise the chances of containing 2019-nCoV infection through careful surveillance, active contact tracing, and vigorous searches for the animal hosts and transmission routes to humans.
As of January 24, 2020, 835 laboratory-confirmed 2019-nCoV infections were reported in China, with 25 fatal cases, the researchers said.
According to the scientists, many of the cases have been linked to the Huanan seafood market in Wuhan, China, where freshly killed game animals were reportedly sold, although the original source of infection remains unknown.
The 2019-nCoV is most closely related to coronaviruses from Chinese horseshoe bats, they said.
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Currently, six coronaviruses (seven including 2019-nCoV) are known to cause diseases of the respiratory tract in people, the researchers said, adding that only SARS and Middle East respiratory syndrome (MERS) have resulted in large outbreaks of fatal illnesses to date.
However, they said there are no specific coronavirus antiviral drugs or vaccines with proven efficacy in humans.
In the first new study, researchers analysed the first 41 patients infected with laboratory-confirmed 2019-nCoV admitted to hospital in the city of Wuhan between December 16, 2019, and January 2, 2020.
The authors combined clinical records, laboratory results, and imaging findings with epidemiological data.
On average, patients were middle-aged, most had visited Huanan seafood market (66 per cent, 27 patients), and most patients were men (73 per cent, 30 patients), according to the study.
Like SARS, the study reported that the majority of cases affected healthy individuals, with less than a third of cases occurring in people with underlying chronic medical conditions such as diabetes (20 per cent, 8 patients), high blood pressure (15 per cent, 6), and cardiovascular disease (15 per cent, 6).
All patients admitted to hospital had pneumonia and most had a fever (98 per cent, 40 patients), cough (76 per cent, 31), and fatigue (44 per cent, 18), it added.
Over half of patients also experienced shortness of breath (dyspnoea; 55 per cent, 22), whilst headache (8 per cent, 3) and diarrhoea (3 per cent, 1) were rare, the study said.
"Despite sharing some similar symptoms to SARS (fever, dry cough, shortness of breath), there are some important differences, such as the absence of upper respiratory tract symptoms (runny nose, sneezing, sore throat) and intestinal symptoms, such as diarrhoea which affected 20-25 per cent of SARS patients," said lead author Bin Cao from the China-Japan Friendship Hospital and Capital Medical University, China.
Approximately one in three patients developed acute respiratory distress syndrome (29 per cent, 12 patients) or were admitted to intensive care (32 per cent, 13 patients), and six died, the scientists added.
Immune system hyper-reaction occurred in critically ill patients, however, the study added that more research is needed to understand how this happened.
Twenty eight patients (68 per cent) have been discharged from hospital as of January 22, 2020, the study said.
The authors noted several limitations of the study, including that due to the limited number of cases, assessing the risk factors for disease severity and mortality is difficult.
In the second paper, which is a first of its kind genetic analysis, scientists studied a family of seven people who presented the hospital with unexplained pneumonia.
They identified 2019-nCoV in five members who had recently visited Wuhan, and in one other family member who did not travel with them.
Only a child, who was reported by their mother to have worn a surgical mask for most of the stay in Wuhan, was not infected, the study noted.
Another child was infected with 2019-nCoV, but showed no clinical symptoms suggesting that individuals may be able to spread infections in the community without knowing that they are infected, the researchers said in a statement.
"Our findings are consistent with person-to-person transmission of this new coronavirus in hospital and family settings, and the reports of infected travellers in other countries," said Kwok-Yung Yuen from the University of Hong Kong-Shenzhen Hospital, who led the research.
Genetic testing found that five patients were positive for the spike protein that novel coronavirus uses to enter cells. Of these, the complete 2019-nCoV genome was identified from clinical samples of two patients, the study said.
None of the family visited food markets or had contact with animals during their stay in Wuhan.
The researchers caution that their findings reflect only a snapshot of one family cluster, and how efficiently this virus is able to spread remains unknown.