The World Health Organization will convene an Emergency Committee meeting over the new coronavirus outbreak that began in Wuhan, China, after more than 300 new cases were confirmed since 17 January, including the first cases to hit other Chinese megacities and provinces. On Tuesday, the virus crossed the Pacific, with the first case in the United States confirmed in Washington State.

The Emergency Committee will meet Wednesday, 22 January, to determine whether the outbreak constitutes a “public health emergency of international concern” (PHEIC) under the International Health Regulations, WHO’s Director General Dr Tedros Adhanom Ghebreyesus said on Monday. An official PHEIC designation would ramp up global resources for the outbreak response, including establishing an official international expert group and WHO outbreak focal points in affected countries. Short of declaring such an emergency, the Committee may also provide recommendations for managing the outbreak as new information about the mysterious disease emerges by the hour.

Along with new reports of the disease in Beijing, Shanghai, and Guangdong Province, South Korea on Monday confirmed its first imported case of the pneumonia-like virus, dubbed 2019-nCoV. Taiwan soon followed suit, with the first case confirmed in a woman traveling from Wuhan on Tuesday.

The United States Centers for Disease Control released a statement Tuesday confirming the first case of the novel virus to cross the Pacific. A patient with recent travel history to Wuhan was tested for the disease after developing symptoms after returning to the US on 15 January.

Some nine people so far have died, and the number of total cases in China has exploded from 41 confirmed cases last Friday to 473 confirmed cases, according to a report issued in the evening Beijing time on Wednesday, by the Chinese state-owned news outlet CGTN.

In the latest update of the CGTN report, authorities said that they had confirmed at least 248 new cases in Wuhan and 12 in the surrounding province of Hubei, 5 new cases in Beijing, 14 in Guangdong Province and 1 in Shanghai, Officials are monitoring suspected cases in four other provinces. Tianjin, Guangdong city, and Henan province confirmed their first cases on Tuesday. The fear is of a much larger spread of the infectious agent, as China approaches its busiest travel season of the year during the Spring Festival.

Zhong Nanshan, the Chinese expert who discovered the deadly SARS virus in 2002, told state-run CCTV network on Monday that they had found the first cases of 2019-nCoV in 14 frontline healthcare workers – one of the groups at highest risk of contracting an emerging disease – confirming the presence of human-to-human transmission.

A national working group of experts from the Chinese National Health Commission said in an official statement released Sunday that they believe the outbreak is “controllable,” and larger epidemic is “preventable. However, the statement notes that authorities are still lacking three key pieces of information to control the outbreak; the source of the outbreak, the dynamics of how the disease spreads, and the likelihood of the virus will mutate into a more transmissible or deadlier strain.

Academics say that the sharp uptick in numbers is consistent with a new report by researchers at Imperial College London that estimates the mysterious disease has already caused symptomatic infections in over 1,700 Wuhan residents since it was first reported in the city on 31 December 2019, while even more people may be asymptomatic carriers. The study modelled likely scenarios for infection in the city of 10 million people, based on documented reports of travelers who had become infected with the virus, total volumes of daily travelers visiting or transiting Wuhan, and a presumed virus incubation period of 10 days.

Experts believe that the original source of the infection were animal hosts sold in a Wuhan live animal market, with most of the original 41 cases reported on 13 January traced back to the Huanan Wholesale Seafood Market in Wuhan, which has been closed since January 1st for health related inspections. On Friday, the World Health Organization confirmed that environmental samples from the market had tested positive for 2019-nCoV – although the exact animal host is still unknown.

However, new cases emerging now have reported having no contact with that particular market. A 35-year old Chinese woman from Wuhan was hospitalized for flu-like symptoms after thermal surveillance at Icheon airport in Seoul, South Korea detected her fever. A statement released by the South Korean Ministry of Health and Wellness said the patient has so far reported no visits to live markets nor direct contact with any known cases while in China, although authorities are continuing to investigate her case.

Similar to the South Korean case, Japan and Thailand’s cases have reported no history of traveling specifically to Huanan Wholesale Seafood Market. New patients in Beijing and Shenzhen have likewise reported no contact with the live market. Still, all patients thus far have recently traveled in Wuhan – which experts say can indicate that either the animal source of the disease is found in more than one market, or person-to-person transmission may be a larger factor than initially suspected.

Once a new virus makes the jump from an animal species to people, it can also evolve to become infectious via human transmission, carried by sneezes, coughs, or other sharing of bodily fluids. That was the case in the 2002-2003 SARS outbreak – which caused over 8,000 cases and 774 deaths. So far, the new outbreak appears to be less fatal than SARS, but authorities and academics are concerned that the virus could mutate into a more deadly strain.

As of 22 January, the new pathogen – belonging to the same family of single-strand RNA viruses as the deadly SARS and MERS (Middle East Respiratory Syndrome) viruses – has claimed the lives of nine people with pre-existing health conditions. Some 17 people remain hospitalized in “severe condition” and 3 in “critical condition” according to a statement released by Wuhan authorities on Tuesday.

This story was published 20 January 2020. It was updated 22 January 2020.

Image Credits: Flickr/Nicolò Lazzati, Imai, N et al. 2019. Estimating the potential total number of novel Coronavirus (2019-nCoV) cases in Wuhan City, China.