More than 65,000 staff will be told that "the NHS needs you" as part of a recruitment drive to help tackle the "greatest global health threat" in a century.
Health Secretary Matt Hancock said those who had recently left the NHS would be able to rejoin immediately, while refresher courses would be put on to get others up to scratch.
He said: "From those I've talked to, I think people can see just how important this is. The training will happen for those who need it over the next couple of weeks, at the same time we'll allocate people to a hospital near them because there's a logistical exercise here as well."
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Health bodies across the UK are writing to those who have left the profession in the last three years with up-to-date skills and experience, asking them to return.
People vulnerable to coronavirus will not be expected to rejoin.
Final year medical students and student nurses are also being offered the chance to take temporary, fully-paid roles to boost working capacity of the NHS.
Recent leavers, including retirees, will be asked about what types of roles they feel they might be able to contribute in.
Maria Caulfield, the Conservative MP for Lewes and a former nurse, tweeted: "I will be returning to the front line in the NHS to support the fight against the coronavirus, important we all help where we can."
Ruth May, chief nursing officer for England said: "As the health service gears up to deal with the greatest global health threat in its history, my message to former colleagues is ‘Your NHS Needs You’.
“Our wonderful nurses in every corner of the country are preparing to change the way we work so that we can provide the right care for the rising numbers of people who will need it.
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“But we can’t do it alone, so I am urging all recent former nurses to lend us your expertise and experience during this pandemic, because I have no doubt that you can help to save lives. And I’m grateful for senior students providing expert care in this time with their NHS colleagues.”
The Nursing and Midwifery Council is writing out to more than 50,000 nurses whose registration has lapsed in the last three years.
The General Medical Council will write to another 15,500 doctors who have left the register since 2017.
Professor Stephen Powis, national medical director for the NHS, said: “Our hardworking NHS staff are working round the clock to get ready for the peak of the pandemic, and today we are calling on former staff to come back and help us.
“It is only right we use every means at our disposal to bolster the frontline in the face of this unprecedented challenge for the NHS.
“By offering to return to the NHS now, these thousands of well-qualified and compassionate people will make more of a difference than ever before – not just to patients, but to colleagues and the wider community.”
Mr Hancock said: "NHS and social care staff are doing an incredible job in the fight against coronavirus, and we want to ensure they are fully supported.
"To further boost the ranks of our NHS, we are now turning to people who have recently left the healthcare professions who can bring their experience and expertise to our health system.
“They can play a crucial role in maximising our capacity to fight this outbreak – and wherever they can help, they will be hugely welcomed."
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