Researchers and policymakers will be striving to maintain a delicate balance to keep the Covid-19 outbreak in check in coming months while allowing life to carry on more normally, the Health Ministry's chief health scientist said yesterday.

Professor Tan Chorh Chuan told Straits Times executive editor Sumiko Tan on ST's daily news talk show The Big Story: "All of us are searching for ways to reach a new equilibrium, a new balance where we can still keep viral spread under control.

"We may not be able to completely get it down to zero, but we keep it well under control (and) in exchange, we are able to function much more normally, and the economy can function more normally, but with a lot more precautions in place."

Prof Tan is hopeful that Singapore will be able to achieve this within the next few months but said there is no place for complacency in the war against a very smart virus: "It still has many tricks up its sleeve.

"And therefore, we have to be really very vigilant. We have to respect our enemy, and therefore we have to continually keep our guard up."

He noted that Sars-CoV-2, the virus that causes Covid-19, is highly contagious and difficult to control, and can spread before infected people show symptoms.

What is worse, the amount of virus shed by patients is at its highest very early on.

Prof Tan, who led the public health response to the severe acute respiratory syndrome (Sars) outbreak here in 2003, said this coronavirus is trickier to deal with than Sars.

This is because - contrary to fears at the time - Sars could not be transmitted through asymptomatic spread, which meant that the world was able to contain it quickly, he added.

Sars also differed in that, while it was more severe, it was mainly spread within healthcare settings such as hospitals.

"Once we were able to get infection control really stringently up in the hospitals, once we were able to curtail the movement of patients and healthcare workers, and we were able to quarantine people very quickly, the outbreak actually was quite quickly contained," said Prof Tan.

But Covid-19, a "community type of infection", is very different.

"It spreads in the community. It spreads through widespread contact between individuals who are circulating around," said Prof Tan.

"And therefore, unlike hospitals and healthcare facilities where you're able to bring public health measures to bear in a very concerted manner, this is a much more diffused problem."

Nonetheless, he pointed out that Singapore learnt many important lessons from Sars, which has armed it better in the fight against Covid-19.

Prof Tan said: "We now have in Singapore many individuals who are administrative leaders, clinicians, nurses, professionals, front-line workers, administrators who have had the experience of dealing with an epidemic, who have the confidence and the knowledge of what to do.

"And because of that, they have also less concerns about getting infected themselves, greater confidence in the protective equipment and therefore somewhat less anxiety."

He added that this was probably the most valuable takeaway from the Sars outbreak as the new systems, research and contact tracing abilities that were developed serve to support "a human resource that is very experienced with dealing with epidemics".

For all that expertise though, there are still concerns.

"What makes us all lose sleep is the constant worry that we will have big explosive clusters that become very hard to control," said Prof Tan.

"Because once the numbers go up very quickly, and if many of them are severely affected, then they will overburden the healthcare system. And that's where outcomes will be worsened and mortality may increase."

The good news, however, is that there are examples from around the world showing the virus can indeed be contained: "If you contain well, the health system need not be overburdened.

"And in Singapore, we are thankful and fortunate that our health system has not been overburdened, that our mortality rates have been low so far, and that we have not had a lot of severe illness amongst the younger foreign worker population."