Around 1.5 million people across England have been warned to stay at home for at least 12 weeks to avoid being hospitalised by the coronavirus.
A raft of new measures on shielding and protecting to help the nation's most vulnerable have been announced by the government.
The new guidance could see people at home for over three months, but who are the 'extremely vulnerable' and what must they do to avoid the virus?
Who are the most vulnerable?
The government has identified 1.5 million people in England at a high risk of being hospitalised because of the coronavirus.
People who fall into the extremely vulnerable group include: organ transplant recipients, people with specific cancers, severe respiratory conditions, rare diseases and those on immunosuppression therapies.
Women who are pregnant with significant heart disease are also included on the list.
The list of conditions includes:
Solid organ transplant recipients
People with specific cancers:
people with cancer who are undergoing active chemotherapy or radical radiotherapy for lung cancer
people with cancers of the blood or bone marrow such as leukaemia, lymphoma or myeloma who are at any stage of treatment
people having immunotherapy or other continuing antibody treatments for cancer
people having other targeted cancer treatments which can affect the immune system, such as protein kinase inhibitors or PARP inhibitors
people who have had bone marrow or stem cell transplants in the last 6 months, or who are still taking immunosuppression drugs
People with severe respiratory conditions including all cystic fibrosis, severe asthma and severe COPD.
People with rare diseases and inborn errors of metabolism that significantly increase the risk of infections (such as SCID, homozygous sickle cell).
People on immunosuppression therapies sufficient to significantly increase risk of infection.
Women who are pregnant with significant heart disease, congenital or acquired.
How do I know if I am in this group?
NHS England will directly contact people they have identified as extremely vulnerable with advice and information via letter or text.
If you think you are an extremely vulnerable person but have not been contacted by Sunday 29 March, you should contact a doctor or your GP.
Dr Paul Johnstone, Director at Public Health England, said: "If you receive a letter it is vitally important that you act on it for your own protection, don’t attend any gatherings of friends or families and don’t go out for shopping, leisure or travel.
"Those of us who are less at risk can play our part in protecting other people by following the government’s advice on social distancing and volunteering to give extra support to vulnerable people who are staying at home."
What is shielding and what should I avoid?
Shielding minimises interaction with those who are clinically extremely vulnerable.
Government guidance says it is important for the extremely vulnerable to avoid contact with anyone displaying COVID-19 symptoms such as a high temperature or cough.
It has also been asked this group stays at home, avoids any gatherings, shopping or travel for 12 weeks upon receiving their letter.
If essential services or a GP needs to be contacted, this should be done via phone or through online services.
The government has also announced Local Support Systems to help those self-isolating receive basic groceries as well as getting community pharmacies to help deliver medicines.
How is it different from social distancing?
Although not everyone has been asked to stay home, the government has advised people to social distance keeping two metres away from one another.
People who are not considered extremely vulnerable can still use public transport for essential travel, go to work if they cannot work from home and go to the shops.
It is strongly advised that gatherings are avoided by all as pubs, restaurants and leisure centres have closed.
Communities Secretary Robert Jenrick MP said: "Public safety and making sure that those most at risk from the virus continue to get the support they need throughout this period is the Government’s top priority.
"People should stay at home, protect our NHS and save lives."
Where should I go for more advice?
For information on how shielding works and how best to protect the extremely vulnerable from the virus, visit the government online guidance.
Health and Social Care Secretary Matt Hancock said: "We are working incredibly hard, day and night, to protect the nation’s public health whilst supporting our NHS so it can continue to look after patients in need of care.
"It is vital that we do everything we can to protect ourselves, our families and our friends from being impacted by the virus. But for those who are at the highest risk in our society, we have to do even more to ensure they’re kept safe.
"Whether it’s going shopping for a neighbour in need, or keeping inside if you know you’re at risk, we all have a part to play in protecting the welfare of those who are most vulnerable."
Coronavirus: Everything you need to know: