A timeline of Covid-19 as the number of confirmed cases increases around the world.
A Chinese virologist who researches coronaviruses in bats has warned that new viruses being discovered are "just the tip of the iceberg".
Shi Zhengli, the deputy director of the Wuhan Institute of Virology, said that research undertaken by governments and scientists around the world needed to be transparent with their findings, and co-operative.
"If we want to prevent human beings from suffering from the next infectious disease outbreak, we must go in advance to learn of these unknown viruses carried by wild animals in nature and give early warnings," she told Chinese TV network CHTN. "If we don't study them there will possibly be another outbreak."
It comes as the Covid-19 pandemic has now infected 5.4 million people globally, and killed 345,000.
Shi Zhengli insists the virus did not leak from her lab. Photo / Supplied
Shi called for greater international co-operation between global scientists and governments, amid a period of high tensions for China and the US.
The Trump administration has blamed the Chinese government for the Covid-19 pandemic, saying the virus originated in Wuhan and the government did not do enough to stop it. Beijing, in turn, has accused the US of seeking to hinder its economic rise.
Both President Donald Trump and his Secretary of State Mike Pompeo have suggested Covid-19 is linked to the Wuhan laboratory - a link rejected by Shi and the Chinese government.
Shi said that the characteristics of the viruses that she has worked with do not match the genetics of the one currently spreading in humans across the globe.
Her research started in 2004 following the Sars outbreak. In 2013, she made a breakthrough in her work when she found bat faeces 96.2 per cent identical to the Sars-Cov-2.
In 2015 she confirmed that it was possible for a Sars-like virus to jump from bats to humans.
Earlier in the month, there were reports Western intelligence agencies including in Australia were examining Shi's work. She maintained Covid-19 was not accidentally unleashed as a result of poor safety standards.
Shi Zhengli. Photo / Supplied
"We have not done anything wrong and we continue to have strong faith in science," she wrote on WeChat on Saturday according to the South China Morning Post, adding that she had not "defected" from the country.
"No matter how difficult things are, there will not be a 'defector' situation as the rumours have said," she wrote.
But in an interview with a US science magazine, Shi admitted to "sleepless nights'' when the outbreak first began.
In the early, anxious days of the outbreak, she remembered thinking it was possible the outbreak came from the Wuhan lab.
Because her studies suggested the subtropical provinces of Guangdong, Guangxi and Yunnan had the greatest risk of coronaviruses jumping to humans from animals — particularly via bats — she remembered thinking, "Could they have come from our lab?"
"I wondered if [the municipal health authority] got it wrong," she said.
"I had never expected this kind of thing to happen in Wuhan, in central China."
As Shi and her colleagues raced to uncover the source of the contagion of the mystery illness, the death toll continued to mount.
Her colleagues used a technique called polymerase chain reaction, to detect a virus by amplifying its genetic material. They soon learned that five of seven Wuhan patients with the mystery illness had genetic sequences present in all coronaviruses. But Shi continued to also investigate whether there was a link with the her own work.
According to Scientific American: "Shi breathed a sigh of relief when the results came back: none of the sequences matched those of the viruses her team had sampled from bat caves."
