In Thailand on January 8, a 61-year-old Chinese tourist from Wuhan became the first reported case outside China. Thailand confirmed a second case a week later, while Japan and South Korea have confirmed one case each.

The Chinese public began calling for more transparency as there remained no reports of cases, confirmed or suspected, within China outside of Wuhan.

On January 20, Chinese authorities confirmed five cases in Beijing and 14 in Guangdong province, which borders Hong Kong. There are now 217 confirmed cases in Wuhan, Beijing and Guangdong, and seven suspected cases in Sichuan, Yunnan, Shanghai, Guangxi and Shandong.

The outbreak has been linked to Wuhan’s Huanan Wholesale Seafood Market and that has since been closed. Some patients, including the woman in Thailand, had not visited the market.

Here is a look at the nature of the outbreak and a timeline of events:

What is limited human-to-human transmission?

This may occur under some circumstances, for example, between an infected person and an unprotected carer in close contact. However, limited transmission under such restricted circumstances does not mean that the virus is easily spread among humans.

Can the new coronavirus cause Sars?

What advice is there for visitors to China?

The World Health Organisation does not advise any travel or trade restrictions on China based on the information currently available. It advised cutting the risk of acute respiratory infections while travelling in, or from, Wuhan by avoiding close contact with infected people, by frequent washing of hands and avoiding close contact with live or dead farm or wild animals.

December 30

The health commission in Wuhan issues a directive demanding hospitals trace and report pneumonia cases of unknown cause after several hospitals in the Hubei provincial capital report patients suffering from a mystery illness.

December 31

The commission announces there has been a cluster of viral pneumonia cases in the city, some of which had been linked to the seafood market, which also sells live animals.

No cases of human-to-human transmission are recorded.

January 1

The seafood market closes. Eight people are punished by police for publishing and spreading “untruthful” information about the pneumonia outbreak.

January 3

Wuhan health authority rules out diseases such as bird flu or adenovirus as the cause of the pneumonia outbreak.

The number of those affected rises to 44, including 11 who are in a serious condition.

The patients are being treated in isolation, and 121 people who were in close contact with them are quarantined.

The Centre for Health Protection in Hong Kong starts to check body temperatures of passengers from Wuhan at Hong Kong International Airport and West Kowloon Station. Suspected cases will be referred to public hospitals for isolation and treatment.

January 4

Singapore’s health ministry announces that a three-year-old Chinese girl who had visited Wuhan has been taken to hospital and isolated as a precaution after being diagnosed with pneumonia. A day later, it is confirmed she is suffering from a common childhood viral illness.

January 5

Wuhan health authority rules out Sars and Mers as the pathogen behind the mystery illness.

The number of pneumonia cases in Wuhan rises to 59 – seven of them serious – while 163 people in close contact with the patients are quarantined.

It emerges that the first case was reported on December 12.

The WHO issues a statement that it has received reports from China’s health authority and advised against any travel or trade restrictions on China.

January 6

Li Gang, director of the Wuhan Centre for Disease Control and Prevention, says more cases are expected as investigations continue.

January 7

Hong Kong announces tougher precautions, laying the groundwork for patients to be quarantined if necessary. New measures include making any “severe respiratory disease associated with a novel infectious agent” a statutory notifiable infectious disease.

January 8

Eight of the Wuhan pneumonia patients are discharged from hospital.

Meanwhile, in South Korea, a Chinese woman who spent five days in the city in December is being treated in isolation after being diagnosed with pneumonia.

January 9

China’s health authority says the outbreak was caused by a new coronavirus from the same family as Sars.

The authority says it has obtained the genetic sequencing of the new virus.

The WHO says an investigation needs to be carried out to find the source of infection, modes or modes of transmission, extent of infection and countermeasures required.

It repeats that it does not see the need for travel or trade restrictions on China.

The Centre for Health Protection in Hong Kong contacts China’s National Health Commission for information about the virus, so the city can carry out accurate tests.

January 10

Professor Yong-Zhen Zhang, with the Shanghai Public Health Clinical Centre and School of Public Health, Fudan University, releases the initial genome sequence of the Wuhan coronavirus. 

January 11

China reports the first fatality – a 61-year-old man with an abdominal tumour, chronic liver disease and pneumonia who died in hospital two days earlier. It says 41 patients are being treated for the coronavirus. The National Health Commission says it will share the genome sequence with the WHO.

January 12

January 13

January 14

It is confirmed that the woman in Thailand had not visited the seafood market linked to the Wuhan pneumonia cases. The WHO says there has been “limited” human-to-human transmission of the coronavirus, but there is the potential for a wider spread. The organisation later retracts its statement and says there is no evidence of human-to-human transmission.

January 15

A second person dies from the virus – a 69-year-old man in Wuhan.

Chinese health officials say that of the 41 people who had tested positive for the new strain of pneumonia, a small number had not been to the seafood market. They say that human-to-human transmission has yet to be confirmed or ruled out. One case is identified as a woman whose husband worked as a market trader and who had the virus before she did.

January 16

Japan confirms that a Chinese national in his 30s, living in Kanagawa prefecture, south of Tokyo, is infected. It is the second case outside China after Thailand. The man returned to Japan on January 6 from Wuhan, where he had been in close contact with a patient.

In Wuhan, four new cases are confirmed, while three patients are discharged from hospital, Chinese authorities say.

January 17

Thailand reports a second case of the new coronavirus, a 74-year-old Chinese woman from Wuhan.

The patient in Japan is discharged from hospital, according to the Wuhan health commission.

Wuhan reports 17 new cases, taking the total number to 62, while another four patients recover. The increase in newly confirmed cases comes after doctors start using a new testing kit.

Meanwhile, there are mounting calls for more transparency as no new cases are reported in mainland China beyond Wuhan.

January 18

January 19

Another 77 new cases are reported in Wuhan.

January 20

South Korea confirms the fourth case outside China – a 35-year-old Chinese woman who arrived at the Incheon International Airport from Wuhan on January 19. She was en route to Japan and has since been quarantined in a designated isolation ward in Incheon, west of Seoul.

Authorities in Beijing confirm five cases, while Guangdong province confirms 14 cases. Seven suspected cases are also reported in Sichuan, Yunnan, Shanghai, Guangxi and Shandong.