Timeline: How the new coronavirus arose and spread

Chinese authorities first investigated an outbreak of respiratory illness in the central city of Wuhan in late December. Here's a look at how information about its cause has unfolded and how it has spread since then.

From 27 cases in Wuhan, China on Dec. 31 to more than 1,200 cases worldwide and 56 deaths by Jan. 26

CBC News Posted: Jan 23, 2020 5:59 PM EST | Last Updated: January 26, 2020

Travellers wearing masks arrive in Seattle on a direct flight from China after a spokesman from the U.S. Centers for Disease Control and Prevention (CDC) said a U.S. resident who arrived from China at the same airport had been the first person in the United States to be diagnosed with the new coronavirus. (David Ryder/Reuters)

Chinese authorities first investigated an outbreak of respiratory illness in the central city of Wuhan in late December.

Here's a look at how information about its cause has unfolded and how it has spread since then.

Dec. 31, 2019

Chinese experts investigate an outbreak of respiratory illness in the central city of Wuhan.
Most patients had visited a seafood market in the city. Authoritiesshutit down and disinfected it.
Total reported cases: 27
Deaths: 0

Jan. 3, 2020

Chinese officials rule out common respiratory diseases such as influenza, bird flu and adenovirus as the cause of the pneumonia cases in Wuhan.
Singapore says it will screen arrivals on flights from Wuhan.
Total reported cases: 44
Deaths: 0

Jan. 5

Chinese officials rule out SARS and MERSas the cause of the mysterious pneumonia.
Total reported cases: 59
Deaths: 0

Jan. 7

Hong Kong adds the mysterious pneumonia to a list of diseases that medical practitioners must report to the government.
Fifteen patients are treated in Hong Kong for fever and respiratory infection after recent visits to Wuhan.
Total reported cases: 59
Deaths: 0

Jan. 9

China's official XinhuaNews Agency says the preliminary lab tests show the pathogen behind the pneumonia cases is a new type of coronavirus, the same family of viruses behind SARS and MERS.
Total reported cases: 59
Deaths: 0

Jan. 11

Wuhan Municipal Health Commission reports China's first death from the new type of coronavirus, a 61-year-old man.
Total reported cases:41 (revised downward from previous day)
Deaths: 1

Jan. 13

A Chinese woman isquarantined in Thailand with a mystery strain of coronavirus, authorities said on Monday, the first time it has been detected outside China.
Total reported cases: 42 (41 in China, 1 in Thailand)
Deaths: 1

Jan. 16

Japan confirms its first case of thepneumonia.
Total cases: 45 (42 in China, 2 in Thailand, 1 in Japan)
Deaths: 1

Jan. 17

A second deathfrom the new coronavirus is reported in China.
The U.S. says it will screen passengers for the virus at threeairports with direct flights from Wuhan.
Total reported cases: 45 (42 in China, 2 in Thailand, 1 in Japan)
Deaths: 2

Jan. 19

A3rd death and more than 100 new cases are announced in China, with reports in Beijing, Shanghai and Shenzhen.
Total reported cases: 201 (198 in China, 2 in Thailand, 1 in Japan)
Deaths: 3

Jan. 20:

China confirms human-to-human transmission of the new coronavirus, after two people in Guangdong caught the disease from family members who had been to Wuhan.
Another death is reported.
South Korea confirms its first case.
Total reported cases: 221(217 in China,2 in Thailand, 1 in Japan, 1 in South Korea)
Deaths: 4

Jan. 21

The first U.S. case of theChina coronavirus is confirmed, a man in his 30s in the Seattle area.
Taiwan also confirms its first case.
Countries in Asia and around the globe begin body temperature checks at airports, railway stations and along highways in hopes of catching people carrying the virus.
Total reported cases: 446 (440 in China, 2 in Thailand, 1 in Japan, 1 in South Korea, 1 in the U.S. and 1 in Taiwan)
Deaths: 9

Jan. 22

Hong Kong quarantines a man after itsfirst preliminary positive test for the new coronavirus.
Macao also reports onecase.
The Public Health Agency of Canada starts asking travellers if they have been in Wuhan, China, in the past 14 days.Signs are planned forairports in Toronto, Montreal and Vancouver to remind passengers to talk to border officials if they have flu-like symptoms.
Total reported cases: 581(571in China, 4 in Thailand, 1 in Japan, 1 in South Korea, 1 in the U.S..1 in Taiwan, 1 in Hong Kong and 1 in Macao)
Deaths: 17

Jan. 23

China closes access to Wuhan and is poised to lock down two neighbouring cities.
The City of Beijing cancels major public events including two well-known Lunar New Year temple fairs.
Singapore reports its first case.
WHO says the new coronavirus is not a global health emergency, but could become one.
The Canadian government urgestravellers to"exercise a high degree of caution in China due to the risk of arbitrary enforcement of local laws," a notice that isone level belowan officialtravel advisory.
Total reported cases:About 650
Deaths: 18

Jan. 24

China's National Health Commission confirmsthe first death outside the central province of Hubei.
U.S. reports its second case.
Total reported cases:830
Deaths:25

Jan. 25

In Canada, health officials confirmthe country's first "presumptive" caseof coronavirus in Toronto.
A man in his 50s travelled from China to Toronto on Jan. 22 and "within a day" became "quite ill" and was admitted to hospital.
Total reported cases: 1,287
Deaths: 41

Jan. 26

China's health minister says the ability of the virus to spread is getting stronger and the number of infections could rise.
Wuhan bansmost vehicle use, including private cars, in downtown areas.
Thailand reports a total of eight infection cases; Taiwan, Australia, Singapore and Malaysia reports four; the U.S. France andJapan 3; Vietnam and South Korea two apiece andCanada and Nepal one.
Total reported cases: More than 2,000 globally, most of them in China
Deaths: 56 in China