DR NORMAN SWAN, REPORTER: It's estimated that a third of the world's 8 billion people are now living under some form of enforced social distancing - with serious consequences for the global economy and that's fuelled criticism that we've over-reacted, as well as a push to open up.

One country that some argue has stayed open without a disaster is Sweden.

This is Stockholm over the weekend - bars are open, people appear to be living a normal life.

Swedes have been asked to socially distance themselves, but it's voluntary.

DR EMMA FRANS, EPIDEMIOLOGIST, KAROLINSKA INSTITUTE: We have this kind of culture of listening to authorities and following their health recommendations.

I think the strength with this policy is that it will be easier to maintain for a longer time period as compared to the more draconian measurements, but it's based on people being responsible.

NORMAN SWAN: Emma Frans is an epidemiologist at the Karolinska Institute. She says that unlike other countries, Sweden is prepared to make some trade-offs while slowing down the spread of the virus.

EMMA FRANS: There is no perfect solution. What we're trying to do in Sweden is to reduce the number of deaths as much as possible but also, maybe, to avoid also very drastic measurements that will also have effects on the public health.

NORMAN SWAN: The trade-off in Sweden is that the coronavirus has run rampant in nursing homes. In total, more than 2,000 people have died.

That compares to just over 80 deaths in Australia, and we more than double Sweden's population.

EMMA FRANS: Well, the strategy of Sweden was to flatten the curve so that the capacity of the healthcare system would be able to cope with all these people needing medical care and this has been quite successful.

The other part of the strategy was to protect the elderly. We haven't been able to succeed in this.

NORMAN SWAN: True to its relative hands-off approach, Sweden does very little testing and almost no contact tracing and quarantining.

EMMA FRANS: The jury is still out on which strategy will be the most successful in the long run.

The problem is that if we do very draconian measurements early on, this will increase the risk of a second wave.

So I think it's not really appropriate to compare the rates in different countries at this early stage.

So we will have to come back in maybe a year or even more than that in order to see how hard different countries were affected by COVID-19.

NORMAN SWAN: The catch is that a lot of people can die in a year while you wait for the results.

But Sweden's not the only country that's tried to avoid a lockdown - Singapore did initially, until their numbers blew up.

PROFESSOR DALE FISHER, UNIVERSITY OF SINGAPORE: I think it's fair to say, every country has actually underestimated the virus. Because all the public health measures that we had in place weren't enough. It still managed to find a weak point in the system.

NORMAN SWAN: The weak point was a large community of migrant workers living in overcrowded dorms.

Last week, cases in Singapore rocketed to a thousand a day.

Now they're in significant lockdown.

DALE FISHER: The reasons we are tightening is not because of just the frank numbers in the community but we're finding a lot of unlinked cases, and we're very good at contact tracing and if we can't link someone, then we can only assume that that asymptomatic, pre-symptomatic disease is causing transmission.

NORMAN SWAN: Dr Dale Fisher is helping to drive Singapore's response and also works with the World Health Organization. His warning - be careful.

DALE FISHER: I think every government needs to look in every corner, every nook and cranny of the country and say, "Where is vulnerable?" Because if you don't find it first, the virus will find it for you.

NORMAN SWAN: Now there's still a lot of debate and confusion over reopening classrooms.

Shutting schools a few weeks ago when our numbers were going up alarmingly did have benefits - mainly, helping parents stay at home and spreading a consistent message about social distancing.

A study of New South Wales schools has been released showing very little COVID-19 virus spread amongst children, and none to teachers.

The study looked at nine students and nine staff who contracted the virus. They had close contacts with 735 other students and 128 other staff. But none were infected.

It's a small data pool but it backs up the Government's advice that opening schools is low risk.