World Health Organization (WHO) received report of several cases of pneumonia in Wuhan City, Hubei Province of China on 31 December 2019. One week later, Chinese authorities confirmed the new virus as a coronavirus, which is a family of viruses that causes severe acute respiratory syndrome, or SARS. It causes a respiratory illness, and can spread from person to person.
Here’s the timeline of how the deadly outbreak is evolving
21 January: Chinese medical workers confirmed infected
15 medical workers in Wuhan have been diagnosed with the virus. Scientists discovered that the virus is more transmissive from human-to-human than was first thought. Chinese authorities and the WHO said that animals seemed to be the most likely source of the virus.
In response to the worsening outbreak, WHO has called a meeting on 22 January to decide whether to declare a public-health emergency.
21 January: First case confirmed in USA
The United States of America has confirmed its first case of the new coronavirus. A 30-year-old man in Washington state has been diagnosed with the virus after a trip to China, making the US the fifth country to report the disease and the first outside Asia.
The US Centers for Disease Control and Prevention (CDC) says that the man did not have symptoms on his arrival in Seattle, Washington, but developed a fever on 16 January and sought treatment. A hospital in Washington state collected blood from the man and shipped it to the CDC, which identified the virus in the samples on 20 January. The CDC is now tracking down individuals who had contact with the man.
22 January: WHO delays decision on emergency declaration
The WHO has postponed decision to declare the outbreak a “public health emergency of international concern”. The move follows a meeting of a committee organized to respond to the outbreak. The same committee will meet again on 23 January.
23 January: Chinese government quarantine Wuhan
Chinese authorities have suspended all travel in and out of Wuhan, the city home to more than 11 million people, in an effort to control the worsening outbreak. Planes, trains, buses and the city’s subway have also stopped running.
Ian Mackay, a virologist at the University of Queensland in Brisbane, Australia, questions whether the city will be able to feed its citizens and manage the increasing number of people who have become sick with the virus, as well as with seasonal influenza, without the free flow of supplies and aid from outside the city. He says the lockdown could have a psychological effect on people.
23 January: Chinese authorities quarantine Huanggang
Huanggang become the second city to be quarantine in China, similar to that in Wuhan. Huanggang has a population of about 7 million people and is around 70 kilometres from Wuhan.
23 January: WHO decides against emergency declaration
The WHO has decided not to declare the coronavirus outbreak a global health emergency.
“At this time there is no evidence of human-to-human transmission outside China,” said WHO director-general Tedros Adhanom Ghebreyesus. “That doesn’t mean it won’t happen.”
A team of researchers pointed to the many-banded krait snake as one possible source of the coronavirus that originated in Asia.
24 January: Second case infection in USA
The US Centers for Disease Control and Prevention (CDC) confirmed a second person had been infected with the new coronavirus. A woman in her sixties returned to her home in Chicago, Illinois, on 13 January after visiting Wuhan, the Chinese city where the outbreak began. She experienced symptoms a few days later.
27 January: Death toll climbs to 80, infection cases rise to 2,700
In China, about 80 deaths have been associated with the virus. Confirmed cases of infection in China have passed 2,700. Cases have also been confirmed in Taiwan, Thailand, Australia, Malaysia, Singapore, France, Japan, South Korea, the United States, Vietnam, Canada and Nepal.
28 January: Infection cases increase by more than 60%, death toll reached 100
The number of confirmed cases in China has jumped up to 4,515, from 2,744, according to the Chinese Center for Disease Control and Prevention. Authorities also report that more than 100 people have died as a result of the infection. Confirmed cases outside China have reached at least 37, but no deaths have been reported outside the country.
28 January: First human-to-human transmission outside China
The new coronavirus has spread between humans outside China for the first time.
A German man acquired the infection from a colleague who had returned from Wuhan. WHO confirmed that a person in Vietnam had acquired the virus from an infected family member. Media reports indicated that a tour-bus driver in Japan who had transported tourists from Wuhan had also tested positive for the coronavirus.
Evidence so far suggests that the coronavirus spreads only through close contact and through saliva droplets, but David Heymann, an epidemiologist at the London School of Hygiene and Tropical Medicine, says there is an urgent need to find out whether it can also spread through air. “The frustrating point is that until now we don’t have all the evidence that can tell exactly how this disease is transmitted.”
29 January: Australian researchers grow virus in cell culture
Researchers in Melbourne, Australia, are the first outside China to announce that they’ve grown the new coronavirus in cell culture. The group at the Peter Doherty Institute for Infection and Immunity says it isolated the virus from the first person diagnosed with the infection in Australia, on 25 January.
The team will now share the virus with research labs around the world recommended by the WHO to help the development of more accurate diagnostic tests and vaccines, says Mike Catton, a deputy director of the institute. “There are some things that are much easier to do when you have the virus,” says Catton.
Although scientists in China say they’ve been able to grow the virus in the lab, they have not yet shared samples with international researchers, they have shared only the virus’s genetic sequence, says Julian Druce, head of the Virus Identification Laboratory at the Doherty Institute.
Catton says having samples of the virus will enable scientists to create tests that can detect specific immune cells, antibodies, that indicate whether a person has been infected with the new virus. Such tests are especially useful for people with mild or no symptoms. Making a test for antibodies is difficult without samples of the virus, he says.
30 January: Death toll jumped to 170, with 7,711 infection cases
The death toll in China jumped to 170, with 7,711 cases reported in the country, where the virus has now spread to each of the 31 provinces.