The coronavirus was not synthesised in a laboratory, the World Health Organisation's (WHO) chief scientist has said.
In an interview with The Straits Times, Dr Soumya Swaminathan said: "What we do know is that this is a naturally occurring virus, that it was not artificially synthesised in the lab."
She added: "I think that scientists have been quite clear about (that), because there are markers in the genome that would have given it away if it had been a synthesised gene."
Dr Swaminathan was speaking on the eve of the annual World Health Assembly meeting yesterday.
Responding to a question on a theory proposed by United States Secretary of State Mike Pompeo that the virus had come from a sophisticated high-security bio lab in China's Wuhan city, she said: "I don't have an opinion on that."
"We know that most likely this came from a bat. What we don't know is how and when it actually transferred from the bat to the human, and what this intermediate animal was, and when those events happened and whether it was a single event or a series of events where it jumped. So those things still need to be investigated by scientists.
"I hope that there can be some international collaborative effort on this because it will definitely help inform future guidelines and steps that one would need to take to prevent such a thing from happening again," Dr Swaminathan added.
"For those things, we're in discussions with the Chinese government about having an international team work with the Chinese researchers, to understand this much better."
Asked about the state of such international collaboration with China, she said there had been active collaboration on many topics, though not this specifically.
"Chinese scientists and researchers have worked with WHO, have worked with other international partners," she said.
The World Health Assembly brings together representatives from the WHO's 194 member states in Geneva to discuss health issues. This year, it is being held for the first time via teleconference, with a major focus on the coronavirus pandemic.
As some countries begin to return to business, Dr Swaminathan stressed the critical importance of accurate information for the public.
When countries open up, their basic principle must be to test people with symptoms, identify the contacts and quarantine them until they are free of the risk of getting the disease, she said.
"Those basic principles will have to be actually followed by governments and cities everywhere. There's no shortcut to that," she said on the phone from Geneva.
"Communities must be involved and engaged, and understand the rationale for loosening and reinstituting measures, because we are now moving into a phase of a long-term change in the way that society is going to function."
"It's really quite a delicate balance, I would say, between creating too much fear and panic, but at the same time underlining the seriousness of this infection," she added.
"Until the time we find a vaccine, and not just find a vaccine but get it to enough people around the world so we develop immunity, there's got to be big changes in the way we behave at home and in the workplace, when we're shopping or taking a holiday or whatever."
She said the public needs to hear the facts. "And it's a changing science as well, because every day, you learn something more about this virus and how it's transmitting and so on, and about its biology, but also advances being made in treatments and in vaccines. And the public health measures that work, and some that don't work.
"So it's important for the leaders to really keep the public well informed... because it's very difficult really to have a behaviour change that one is expecting at this scale without a massive effort in communication. And, I think, also leading by example," she said.
"People and communities must really understand why governments are doing certain things, and why it's important for individuals to do certain things - because they're protecting themselves, they're protecting others. And if people do not follow those measures, then you could be back in a very bad situation again."
Q&A with chief scientist
Q: We seem to be living in a new age of significant science denialism. Do you think this has actually hindered the response so far or is it just a sort of fringe issue?
A: This is a challenge globally and has been for some time, and the WHO (World Health Organisation) has been dealing with it in the area of immunisation, vaccination, where we have seen across the world, particularly in higher income countries... in the last couple of years, we have seen dramatic increases in measles cases and measles deaths because there are more and more people who have not immunised their children.
So, in fact, WHO came out very early in the Covid-19 outbreak with the (term) infodemic, which is not only the overload of information, but misinformation and misconceptions being spread, and also conspiracy theories and rumours, and all of that.
We started working with many of the big social media tech companies like Facebook and TikTok and WhatsApp and Instagram to put in place mechanisms so that when someone comes and searches for Covid-19, they are actually automatically directed to sites which provide reliable information...Despite that, there is a lot of misinformation out there and that actually does make things more difficult for governments to do the right thing.
I think the fringe elements make a lot of noise... but even if you look at anti-vaxxers (those who oppose the use of vaccines), it is still a minority. I think we have seen in countries where scientists have been communicating well to the public, there is overall less… fear and panic.
Q: Is it fair to speculate that we might end up in a situation of herd immunity anyway as a sort of default?
A: From the data we have so far from places which have had big outbreaks… we have seen in the range of 5 per cent to 10 per cent of the population seems to have been exposed. Which means that 90 per cent of all of us are still susceptible. In order to get herd immunity against this virus, you probably need more than 70 per cent or so of the population to have protective antibodies.
So, we are very far away from getting there. And there are two ways of getting there. One is through a process of natural infection. You go through waves of this repeatedly over a few years. Or the better option would be, of course, to do it through vaccination. Because we have seen that if you allow the natural infection route to happen… the price in terms of death would be very high.
Q: What is the single top message that people need to hear?
A: The huge sharing of knowledge and data right from the beginning of this has really helped people around the world to understand this and, of course, to develop new drugs and treatments... even people who have worked in global health for a very long time have said this is unprecedented global solidarity and collaboration. It gives hope that the Covid is a global problem, and it is in everybody's interest to find a solution, that there will be a solution.