China has reported four more cases of pneumonia in the city of Wuhan, following the outbreak of what is believed to be a new strain of a coronavirus, Reuters reports.

New cases are in stable condition

According to the Wuhan Municipal Health Commission, all four individuals who were diagnosed on Jan. 16 are currently in stable condition.

China has seen 41 infections and two deaths since the start of January.

The total number of infected cases is estimated to be at 1,723 as of Jan. 12, according to a report by scientists from the MRC Centre for Global Infectious Disease Analysis at London's Imperial College.

Authorities in Wuhan did not reply Reuters' questions on the report by press time.

Number of infected within Wuhan inferred from external cases

As for the figure of 1,723, MRC Centre's website stated that the report had taken the number of infected outside the city of Wuhan -- two cases in Thailand and one case in Japan -- to infer the number of cases within the city, based on international travel data from its airport.

Size of Wuhan outbreak of a novel #coronavirus estimated from the three cases detected outside China: Likely to be over 1000 cases. @imperialcollege @mrc_outbreaks report released today

🔰 https://t.co/7A77NXZ3iw pic.twitter.com/u0dUnMs9hA

— MRC Centre for Global Infectious Disease Analysis (@MRC_Outbreak) January 17, 2020

https://twitter.com/alvinllum/status/1218391279395950594

Professor Neil Ferguson, one of the authors of the report, was quoted by BBC saying it was the overseas cases that caused him worry.

"For Wuhan to have exported three cases to other countries would imply there would have to be many more cases than have been reported."

Possibility of human-to-human transmission considered

He added that while it was "too early to be alarmist", the possibility of human-to-human transmission should be more seriously considered.

Thus far, Chinese officials have stated that none of the cases have been the result of the virus spreading between people, BBC further highlighted.

Rather, the outbreak reportedly stemmed from infected animals at the Huanan Seafood Market in Wuhan, the officials said.

MRC Centre added that the market has been closed since Jan. 1 in an effort to contain the outbreak.

Some patients did not visit the market in question

However, two of the victims in Japan and Thailand claimed that they did not visit the market in question.

If true, it would suggest that the virus has spread to other parts of the city.

Separately, Singapore's Ministry of Health (MOH) announced on Jan. 17 that two Singaporeans had been admitted for assessment and treatment after they were suspected of having contracted the pneumonia virus.

While both have travel history to Wuhan, they did not visit the market associated with the cluster of pneumonia.

They have since been cleared of the coronavirus strain associated with the outbreak.

On Jan. 18, however, another Singaporean who had visited to Wuhan was admitted for further investigations after contracting pneumonia.

Screening started in some countries

AFP reported that some countries have started putting in place measures to screen inbound passengers.

The U.S. has announced that it will start screening at three airports in San Francisco, Los Angeles and New York to detect passengers who have arrived in the country via connecting or direct flights from Wuhan.

As for Thailand, it has begun screening passengers at Bangkok, Chiang Mai, and Phuket, with similar measures planned for Krabi as well.

The virus itself is suspected to have come from the same family as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). 

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Top Photo by Gary Todd via Flickr