Keeping everyone at home to stem the transmission of Covid-19 has substantial social and economic costs, and is likely to disproportionately impact lower-income and vulnerable groups, said National Development Minister Lawrence Wong.

"They are also less likely to be able to telecommute for work. So staying home will clearly affect their incomes and livelihoods. Being isolated at home for long periods is also not good for their health and overall well-being," he noted.

That is why the Government considered very carefully before implementing the circuit breaker and later extending it for a month till June 1, he said in a ministerial statement in Parliament yesterday.

While it was a difficult decision to implement and extend the circuit breaker as businesses and workers were already hurting, he said the Government decided to do so to break the transmission chain and slow down the spread of the coronavirus.

From next Tuesday, some gradual easing of the measures will be allowed, such as letting barbers and hairdressers reopen.

But the key circuit breaker measures will largely remain till June 1, said the minister, who co-chairs the multi-ministry task force tackling Covid-19.

"I must strongly caution that the easing of some measures in the coming weeks cannot be taken as a signal that we can now take it easy and start to go out more," he said, reiterating that the fight against Covid-19 is far from over.

"The virus can flare up again any time. We cannot afford to slacken. But we must stay vigilant, maintain our discipline, continue to stay home and minimise our contact with others."

Singaporeans should also expect more challenges in the fight against Covid-19, which may require further adjustments in the measures and precautions taken, the minister said.

The Government will also have to quickly adjust risk assessments and measures as it learns more about how the virus is transmitted.

Mr Wong acknowledged that it can be difficult to keep up with all the changes.

"We are dealing with a new virus, and scientists everywhere are discovering more about the virus - even today - and the disease it causes," he said.

He added that the latest evidence and medical advice, and the impact on people, are considered before changes are made.

For instance, the Government updated its guidance on masks as it learnt more about the virus, eventually making it a requirement for everyone to wear masks when they go out. It also calibrated measures, and allowed people to go out to exercise amid the circuit breaker, as there is no local evidence of transmission among people exercising in the open, said Mr Wong.

He noted that people were also not required to wear masks when they exercised, as long as they observed safe distancing.

This measure is in line with what the Czech Republic, one of the first European countries to make mask-wearing mandatory, has done.

Mr Wong noted that some have said that Singapore should not bother with such careful calibration of measures, and that it should have just gone for a "full lockdown".

But countries that imposed lockdowns have implemented varying measures, even if they use the same term, he pointed out.

"What is more important is to understand the specific measures that are needed in our own context and circumstance."