IT could take six months before the UK can revert to normal life, a UK medical chief has said.

Deputy Chief Medical Officer Dr Jenny Harries said the UK has only had one week of lockdown  and that the prime minister said the situation would be "reviewed" after three weeks.

But she adds it would be "quite dangerous" to then revert to normal life.

"If we stop then all of our efforts will be wasted", she adds.

She says that measures may be reduced gradually over time.

Dr Harries says it might be two or three months before we see the longer-term impact, and about three to six months before we are can see when we can get back to normal life.  But she said there was a "lot of uncertainty" in even that and she warned it is "plausible" it could take longer.

She said: "For all of us it has taken some time to get used to this new way of living, to practice social distancing, and we stick to that. 

"As a population we have evidence we are getting better at that.

"The issue of the three weeks is to review where we are and if we have an impact jointly on the slope of the [cases] curve.

"To make it clear, if we are successful and  have squashed the top of the curve, we must not then revert to our normal way of living. that would be quite dangerous.

"If we stop then, all of our efforts will be wasted and we could potentially see a second peak.  

"Over time, probably over the next six months, we will have a three week review and see where we are going.

"We need to keep that lid on, and gradually we will hopefully be able to adjust the social distancing measures and gradually get back to normal.

"So three weeks for review, two or three months to see if we have really squashed it and about three to six months ideally, and lots of uncertainty in that, to see at which point we can get back to normal. And it is plausible it could go further than that."

She stressed that did not mean the country would be in total lockdown for that period of time.

Earlier, communities secretary Robert Jenrick said all parts of the UK are now on emergency footing which is an "unprecendented step in peace time".

"We have not done anything like this since the Second World War," he said.

Last week, Prime Minister Boris Johnson said the "tide would turn" against the virus in 12 weeks, and he was asked if this is still the same.

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He said: "Nobody is pretending this will be over in a few weeks.

"But what the prime minister said in the past, and what I will reiterate today, is if we all play our part, if we all follow the very clear medical advice... then we can turn the tide of this virus."

He said that everyone in the UK has "the power to influence the course of events".

He says if people "want to protect lives and protect the NHS" then they "must take heed of the medical advice".

"This is on all of us. We all have a responsibility to protect each other. We just need to follow the advice in the days and weeks ahead," he said.

Dr Harries says the virus is like a "moving feast" and when we see it tackled is "dependent on the actions we take as individuals and collectively as a population".

She says she hopes the "proof of that will come in two to three weeks" when experts can see if the measures put in place have worked.

Mr Jenrick calleed on those without local support to register for help on the government's website. He says the NHS can deliver medicine, and distribution teams can deliver food - to those who request it.

He added that 50,000 food parcels are being sent out this week.