Coronavirus: When will the lockdown end and how do we get out of it?

When Boris Johnson put the UK into lockdown on 23 March, he said it would last for an initial three weeks.

The law says that deadline is reached on Thursday so this week the government will be reviewing whether social distancing measures are working.

But if a decision to change the guidelines is taken, how will the UK government relax the rules and reopen an economy that's been shut down by COVID-19?

Last week, leaders of Norway, Denmark, Czech Republic and Austria announced plans to relax restrictions in their countries. The plans will be put in place in the coming weeks.

Experts had predicted the coronavirus pandemic would reach a peak on Easter Sunday in the UK, based on mathematical modelling. That was the same day the death toll passed 10,000 people.

The outbreak then looked likely to plateau at that level for more than a few days. But scientists and medics then pushed that timeline back, indicating that the UK might not reach a peak for another week at least.

Bronwen Maddox, director of the think-tank, Institute for Government says until a vaccine is created there won't be a "real exit plan back to normal life".

She added: "They [the UK government] will try with models to very carefully build up a picture of what happens if you release this or that, but they really don't want to encourage people to lift it all at once.

"There is some debate about whether schools are or aren't a big help in containing infection at the moment.

"We're going to have to start looking at both areas of greatest economic cost and least medical risk in trying to edge our way out of this."

One of Germany's prominent think-tanks, Ifo Institute for Economic Research, suggests that industries with the highest economic value - such as telecommunications and carmakers - should be prioritised, while sectors that can afford to have employees working from home should continue to do so.

Their report suggests select regions with low infection rates and health care centres that haven't been overburdened could lead the way with a gradual reopening.

Any decision in the UK about whether to loosen the lockdown is likely to be complicated by the fact that different parts of the country are at different stages in their outbreaks.

When restrictions were imposed on 23 March, the prime minister and his scientific advisers said the capital was two weeks ahead of the rest of the UK.

Indeed, on lockdown day, London accounted for more than one in four daily reported deaths in England and more than one third in the UK. Over the last week or so that balance has shifted as other regions began to catch up.

Hospital admissions tell a similar story: the trend in London is down but the North West, the Midlands and the North East & Yorkshire have been regularly recording 20-40% daily increases.

It is a similar picture in the other UK nations, notably Scotland and Wales where Health Minister Vaughan Gething recently suggested the virus was moving from the east to the west of the UK.

All this has brought speculation of a phased release to lockdown in which London, for example, might be freed first, while other regions and cities will still have to follow the rules.

Sky News data journalist Isla Glaister said: "Of course, this comes with potential problems. What if Londoners start travelling to other parts of the country? And, will people in areas still under restrictions resent those who aren't?

"Each day gives the scientists more information about the epidemic's progress but, as people see the curve start to flatten they may become impatient to get back to normal life.

"The government has always said the timing of when lockdown is lifted is crucial - but so is how it is done and getting the balance right means it could be later, rather than sooner."

Denmark will become one of the first to relax restrictions in Europe. But it was also among the first going into lockdown, on 11 March.

The country's disease control research centre Statens Serum Institut (SSI) formed an expert group to develop mathematical models and study the impact of relaxing restrictions on specific dates.

The Danish approach has been to relax restrictions enough to satisfy the population's demand for incremental freedom. The government sets out the restrictions it wants to lower and SSI sets the date at which this can be safely done.

:: Listen to the All Out Politics podcast on Apple Podcasts, Google Podcasts, Spotify, Spreaker

Using SSI's analysis, the Ministry of Health said the country could open day care centres on 15 April, as well as allow students facing final exams in secondary education and college to attend school.

It insisted that businesses continue working their employees from home wherever possible as their models were extremely sensitive to "sustained compliance with social distancing" measures.

The city of Wuhan - the epicentre at the start of the pandemic - has emerged from 76 days of lockdown with authorities still warning the threat of further infections remains far from over.

The rest of China went into lockdown starting in February and began loosening restrictions a couple of weeks later, except for Hebei province, where the COVID-19 pandemic began.

According to the investment bank UBS, around 30% of scenic spots and some museums in China have reopened to the public but cinemas and theatres have been asked to shut after a government u-turn.

Most large events are still prohibited, and social distancing continues to be encouraged to prevent a relapse in infections.

Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading warns cases do flare up in China, Japan and Singapore despite restrictions being relaxed.

He added: "I think we will lift controls and then have to reintroduce them at some point.

"The (UK) government will have to sit down with advisers - their mathematical modelers - and decide how best to let the foot off the brake."