An updated analysis today casts doubt on whether China will be able to contain its novel coronavirus (2019-nCoV) epidemic, as the country reported 440 new cases and Australia and Malaysia announced their first detections.

In scientific developments, a new analysis of 24 genetic sequences suggests that the outbreak probably began with a single introduction of a virus, presumably in the Wuhan market in November or early December, triggering a quickly spreading outbreak in humans that has now topped 1,400 cases in China.

Sustained transmission fueling outbreak

The new analysis on 2019-nCoV transmissibility was released today by a group based at Imperial College London that made two earlier projections on the number of symptomatic illnesses in Wuhan.

The report focuses on transmissibility, and the scientists say sustained human-to-human transmission is the only explanation for the large-scale outbreak in Wuhan. They add that today's report is an extended version of what they shared with the World Health Organization, governments, and academic networks earlier this week.

They estimate that the reproduction number (R 0 ), the average number of illnesses spread by one infected person, is 2.6 (range, 1.5 to 3.5). Also, the experts said transmission patterns are probably variable, with some people infecting several others, while some don't, a pattern seen with SARS (severe acute respiratory syndrome) and MERS-CoV (Middle East respiratory syndrome coronavirus).

Control steps in China would need to block 60% of transmission to control the outbreak, the researchers projected. Without drugs or vaccine, shutting down the outbreak depends on quickly finding and isolating sick people.

"It is unclear at the current time whether this outbreak can be contained within China," they wrote, emphasizing that key questions remain, such as how well residents adopt recommended risk-reduction steps, how severe the disease is, and how readily people with mild disease can pass the virus to others.

They urged health officials, if possible, to cast a wide net for isolating and testing suspected cases that involve only mild to moderate disease.

China confirms 444 new cases, 16 more deaths

China's Centers for Disease Control and Prevention (China CDC) today reported 444 more cases this morning, spanning 29 provinces, raising the country's official outbreak total to 1,287. So far, 237 people have severe infections, and 16 more people died, pushing the fatality count to 41.

The new totals include the first case from Qinghai province, the 30th to report a case. Hubei province, which includes Wuhan, is still by far the hardest-hit area, accounting for more than half of cases, followed by Guangdong, Zhejiang, and Chongqing.

Websites that tally newly reported cases throughout the day reflect as many 1,409 infections, 42 of them fatal.

China's President Xi Jinping today held a politburo meeting to discuss steps to contain the epidemic, saying on state television that the outbreak is accelerating and that the country is facing a "grave situation," Voice of America (VOA) news reported.

In other developments in China, the Wall Street Journal (WSJ) reported today that the US government is working on a plan to airlift American citizens from Wuhan, which has been on lockdown since Jan 23. The flight is expected to leave tomorrow and will have US medical personnel on board to monitor passengers.

In a similar diplomatic effort, French officials are working on a plan to bus French citizens from Wuhan to Changsha in Hubei province, the South China Morning Post (SCMP) reported today.

Australia, Malaysia note first infections

Australia today reported its first four cases, London-based The Guardian reported today, citing country health officials. The first was a 50-year-old Chinese man from Melbourne who arrived in the country on Jan 19 from Guangzhou in Guangdong province after spending time in Wuhan. Officials said he didn't have symptoms during his flight.

The three other cases were detected in New South Wales state, including in a man in his 50s who arrived in Sydney on Jan 20 from Wuhan. Another patient is a man in his 30s who arrived in Sydney from China on Jan 6 but didn't have symptoms until Jan 15; he didn't visit Wuhan but had contact with a sick person from that city. The third is a man in his 40s who arrived in Sydney on Jan 18 after being in Wuhan.

Malaysia reported its first three cases today, all of whom are family members of a Chinese man whose 2019-nCoV infection was recently confirmed in Singapore, according to a report today from The Star, which quotes the country's health minister.

The three—part of a group that traveled from Guangzhou, China, on Jan 20—were asymptomatic, but lab tests showed they were infected with the virus. The patients are the Singapore patient's 65-year-old wife and their two grandchildren, ages 2 and 11.

Meanwhile, Japan today reported its third imported case. The patient is a woman from Wuhan who arrived in Japan on Jan 18, Kyodo News reported, citing Japan's health ministry.

So far, at least 37 exported cases have been reported from 13 areas outside China's mainland.

Gene analysis hints at recent spillover

A new analysis from researchers at the open-source pathogen genome analysis project Nextstrain, based on 24 genomes of 2019-nCoV that have been shared, found a lack of diversity that points to a single spillover from animals to humans or a small number of spillovers involving very similar viruses. The researchers are from the infectious diseases division at the Fred Hutchinson Cancer Research Center in Seattle and Biozentrum at the University of Basel in Switzerland.

The animal source of the outbreak hasn't yet been confirmed, though separate recent genetic analyses found that 2019-nCoV is most closely related to earlier viruses found in bats.

In the new findings, researchers suspect that the jump from animals to humans probably occurred recently, in November 2019 or in early December. Chinese health officials detected the outbreak in the middle of December, following a cluster of suspicious pneumonia cases in patients connected to a Wuhan seafood market, which also sold various live animals.

Some of the sequences confirm human-to-human transmission, including three sequences from Shenzhen that came from a single family, plus two nearly identical sequences from Zhuhai in Guangdong province, also from a single family.

The group praised teams that have shared the genomes, which were all submitted to GISAID (the Global Initiative on Sharing All Influenza Data). "We would like to acknowledge the amazing and timely work done by all scientists involved in this outbreak, but particularly those working in China," they wrote.

See also:

Jan 25 Imperial College London report

Jan 25 China CDC report

Chinese medical community (DXY) 2019-nCoV tracking website

Jan 25 VOA news report

Jan 25 WSJ story

Jan 25 SCMP story

Jan 25 Guardian story

Jan 25 Star story

Jan 25 Kyodo News story

Jan 23 Nextstrain report