The message was at the heart of the Government's coronavirus strategy from the very start of lockdown: protect the most vulnerable. Although many, such as those with diabetes or heart disease, were told they were at risk and should take social distancing seriously, there was a group that were in even more danger.
These patients - among them those with cancer and severe lunge diseases, those who'd had transplants or who were on drugs that suppressed the immune system - were told they needed to 'shield' from the virus. And, for them - about 2.2million Britons - lockdown has been particularly arduous.
They were advised to stay inside at all times and not open the front door, let alone go out for daily exercise. Reliant on food deliveries and kind neighbours, thousands who live alone may not have seen another soul for months.
Even when politicians changed tactic at the start of May - from 'stay home' to 'stay alert' - the advice for this shielding group remained consistent. The risk of venturing out and potentially catching the virus, they were told, is simply not worth it.
Around 2.2million Britons were told by the Government they needed to 'shield' from the virus at the start of lockdown (stock photo of a girl visiting her grandparents)
Except, now, the Government say, it is. In a surprising U-turn, Boris Johnson announced last Sunday that it is now safe for even the sickest Britons go out once a day. The common-sense rules about maintaining strict social distancing and handwashing still apply - but there the guidance ends, apart from one caveat: 'Shielding is for your personal protection, and it's your choice to decide whether to follow the measures we advise.'
The justification was that levels of the Covid-19 infection, and the transmission rate, had reduced. Yet experts are not so convinced it is safe.
The Royal College of GPs issued warnings last week, advising vulnerable Britons to remain 'extremely cautious'. Dr Stephen Griffin, an associate professor at the University of Leeds school of medicine, criticised the relaxation, saying it 'seemed to lack any obvious rational'.
And stuck in the middle are the patients - anxious, fearful and confused about what to do next. Now, nearly 50 leading charities supporting the most vulnerable have written to the Government, demanding 'clear, consistent advice' for shielders about how to protect themselves.
As Dr Griffin asks: 'How are shielders supposed to judge whether it is indeed safe for them to alter their behaviour?'
According to medics, it's not only the risk of catching the disease - dependent on the rate at which it's spreading - that matters.
'There's also the risk of you, as an individual, becoming seriously ill if you do catch it, which depends on your underlying condition,' says Graham Burns, president elect of the British Thoracic Society and a respiratory physician in Newcastle.
According to medics, it's not only the risk of catching the disease - dependent on the rate at which it's spreading - that matters (stock photo of a boy with his grandfather)
Understandably, it's not practical for the Government to compute risks for each one of the several hundred specific health conditions shielders may suffer from. So how can each of us decide, when we have serious and justifiable concerns, whether it really is safe to go back outside?
The truth is, it's difficult to know for sure. There is only very limited data on what the actual risk to people in the most vulnerable groups is - because they have been shielding so well, most haven't come into contact with the virus.
Their initial risk was also calculated on the basis of flu data - which, it is now known, is not comparable.
Danny Altmann, professor of immunology at Imperial College London, is worried about the Government's new 'devil-may-care approach'.
'We've moved away from genuinely trying to be led by empirical science to one which involves following your own common sense. But patients will have to be very informed to navigate this.'
In a bid to help remove some of the guesswork, we've brought you what the Government hasn't: specific facts about the risks facing thousands of patients who suffer some of the most common, serious health problems.
Of course, every case is unique and patients should ask for advice from their own specialist or from trusted health charities, but our guide should help you make an informed decision about whether the risk of that walk in the park is truly worth it...
GOOD NEWS FOR SOME CANCER VICTIMS
Roughly 2.5million people live with cancer in the UK, many of whom may be undergoing treatment, such as chemotherapy, that compromises their immune system.
Since the beginning of the pandemic, it's been assumed that those with cancer are at a higher risk of developing serious Covid-19 illness. The same is true for flu.
Early studies from China appeared to confirm they were both more susceptible to the virus, and more likely to have severe symptoms. As a result of the research, thousands of UK cancer patients had their treatment deferred or delayed.
But a new study of 800 British cancer patients who tested positive for Covid-19, published last week in The Lancet, suggested there may not be a link between cancer treatment and deaths from coronavirus.
The majority, 52 per cent, had only mild illness. While roughly a third died, these victims were 'significantly older', male and had other health problems such as cardiovascular disease and high blood pressure, all of which are known risk factors for Covid-19. In other words, cancer itself was not deemed to have increased the risk.
Professor Siow-Ming Lee, a lung cancer specialist at University College London, said: 'It's worrying that people may put their fear of Covid-19 before their fear of cancer. Most people with coronavirus recover - and that includes people who also have cancer. If you're under 60 and without any other problems, you shouldn't delay or defer your treatment.'
FIT AND OVER 70? GOOD NEWS - YOU'RE NOT HIGH RISK
Age is overwhelmingly the biggest risk factor for coronavirus. More than half of the deaths have been in the over-85s, while a further 36 per cent are older than 60, according to Professor Janet Lord, director of the Institute of Inflammation and Ageing at the University of Birmingham.
Older adults have a weaker immune system which makes them more susceptible to viruses, and get sicker if infected, she says: 'Part of the reason for this is exaggerated inflammation we see in older people, caused by the response of the immune system, and also the aged lung, which is less resilient to damage induced by infections.'
But while the over-70s were initially advised to stay at home, that guidance has now relaxed and, unless they have specific conditions that put them at risk, they are considered no more vulnerable than the rest of the general population.
That's according to the Government guidance, at least Prof Lord said: 'Lots of people in the over-70 group are fit and healthy, and their risk is much lower than for someone in their 60s with lots of health problems. You still have to be careful, but as long as you're fit and healthy and you keep to the two-metre social distancing rule, you'll be fine.'
She added that exercise and seeing other people had 'strong mental health benefits and will reduce stress, which also has a powerful effect on the immune system.'
Yet the study recommends patients 'continue to shield', just in case. Prof Lee also added patients should take 'whatever precaution to prevent catching the infection' - including continuing to adhere to social distancing, handwashing and wiping down surfaces.
Those with some specific cancer types are more likely to die – lung cancer has been seen to increase the risk by 50 per cent, and blood cancers by 57 per cent.
A further UK-based study, involving data from 14million people, suggests that blood cancer - including leukaemia, multiple myeloma and lymphoma - increases the risk of dying from coronavirus by 'about 3.5 times', according to Alasdair Rankin, director of research at Blood Cancer UK.
The condition affects cells in the immune system, which limits the body's ability to fight infection. Some patients need stem cell transplants, which wipes out the immune system completely in order to reboot it, leaving them defenceless against viruses such as Covid-19.
'We think that, so far, shielding has been really effective in protecting people from infection,' Rankin said. 'If you're on active treatment you need to be more careful.'
Interestingly, children with cancer do not appear to be adversely affected. Out of 1,700 children receiving treatment, just 46 tested positive for the virus, in one study. Of those, 15 per cent had no symptoms, three-quarters had only mild symptoms such as a cold or slight temperature, and just two needed treatment in intensive care. Both recovered.
Dr Bob Phillips, honorary consultant in paediatric oncology at the University of York, said: 'In some cases, the risk may not really be any different from a normal child.'
THREAT TO ORGAN TRANSPLANT PATIENTS
About 5,000 organ transplant operations take place every year in the UK. Patients spend the rest of their lives on drugs which suppress the immune system to prevent the organ being rejected, but this makes them more susceptible to infections such as Covid-19.
Data on specific risk for this group is limited, partly because patients are successfully shielding, so few have actually caught Covid-19.
But Adnan Sharif, consultant transplant nephrologist at Queen Elizabeth Hospital Birmingham, and a trustee of Kidney Research UK, warned kidney disease patients travelling to hospital three times a week for dialysis are indeed 'far more badly affected'.
He says: 'We're suggesting patients err on the side of caution and continue to get someone to do their shopping for them, or have a delivery.'
If it is possible to go outside for a walk and keep two metres from others - or, ideally, come into contact with no one - then it could be considered, he adds.
Patients with chronic autoimmune diseases such as multiple sclerosis (MS), lupus and rheumatoid arthritis have been told they're not at greater risk - unless they're among those also taking drugs to suppress the immune system.
These patients are being advised to still take extra care.
But Prof Altmann said the risk is still theoretical - again as too few in these groups have actually caught Covid-19, presumably due to shielding. So, as more evidence is gathered, guidance could change.
Our guide should help you make an informed decision about whether the risk of that walk in the park is truly worth it (stock photo of children seeing their grandparents)
WHY NOT ALL LUNG DISEASES ARE EQUAL
The lungs are ground-zero for coronavirus - the place where it invades the millions of tiny air sacs, causing inflammation and preventing the body from taking up oxygen. It is well documented that those with serious lung problems, such as cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD) and severe asthma, are even more vulnerable. But not all are equally affected.
Studies estimate that roughly a fifth of hospitalised Covid-19 patients have COPD, and they are, on average, 17 per cent more likely to die than the average person. Asthma, on the other hand, doesn't appear to increase the risk of death, although it does make an admission to hospital more likely.
Interesting, too, is that cystic fibrosis, a life-limiting condition which causes mucus to clog the lungs, seldom appears in the data.
'There's a shockingly small number of cystic fibrosis patients who've had a positive Covid-19 diagnosis,' says Dr Graham Burns, Consultant Physician in Respiratory Medicine at Newcastle hospital.
'There's some data showing the vast majority of patients who got it recovered well. Because most people with CF are young, it looks like age is trumping the underlying disease factor.'
Dr Burns said that meant some respiratory patients, 'may have a little more freedom than they expected' to get out and about more. But he cautioned them to speak to their doctor first.
'All of us working in the field are consistent in saying, 'You are at increased risk' and we recommend following the shielding advice. We don't anticipate that changing in the near future, as we're not confident the prevalence of the virus is on its way down permanently.'
HEART DISEASE AND PREGNANCY RISKS
Since the start of the pandemic, there's been much debate about the vulnerabilities of pregnant women. Although not in a shielding group, they are categorised as 'vulnerable' and told to take extra care.
The justification for this was largely because of their increased susceptibility to severe flu symptoms. But so far there is no evidence that coronavirus causes serious effects to pregnant women, and cases of Covid-19 transmission to unborn babies, through the placenta, is very rare.
Andrew Shennan, professor of obstetrics at King's College London, said there were five maternal deaths related to Covid-19 among 80,000 births during a six-week period. 'There's no doubt there's an impact, it's just not a big one,' he said.
'High blood pressure causes one death in 2,000 pregnancies, while corona is one in 16,000.'
However, if you're pregnant and suffer cardiovascular disease, it's right to consider yourself extremely vulnerable.
'We don't have the data but there's strong logic which suggests pregnancy, cardiovascular disease and coronavirus is a bad thing combined,' says Prof Shennan.
'If you're pregnant, your heart and lungs are overworking anyway and you're six times more likely to get blood clots. And we know that Covid-19 further increases the risk of clotting. You're also taking deeper breaths when pregnant, so it's a triple whammy. If you're one of those women with heart disease, stick to the guidelines and stay shielding.'
Q&A: WHY IT'S SAFER OUTSIDE AND THE BALD FACTS
Outside, the air is better ventilated than when indoors. This means droplets are more likely to fall to the ground and be dispersed (stock photo)
Why are you less likely to catch the virus outdoors?
Covid-19 is transmitted in tiny droplets, spread through coughs, sneezes and loud talking.
It can also spread if droplets end up on surfaces and people touch them.
Outside, the air is better ventilated than when indoors. This means droplets are more likely to fall to the ground and be dispersed. Gusts of wind and a gentle breeze can help with this.
It is also easier to stay two metres apart from others while outdoors, and you're less likely to touch surfaces that may carry traces of the virus.
Does being bald really increase the risk of severe Covid?
Last week, researchers suggested that bald men may be at a higher risk of suffering from severe Covid-19 symptoms, which was based on two small studies. In one, three-quarters of 41 men admitted to hospital with Covid19 were noted to be bald. The other found a similar association.
But if you've lost your hair, don't panic. We already know that men and older people are more at risk from Covid-19, and given that it is very common for men to lose their hair as they age, it follows that a number of bald men could be severely affected by the disease.
And only a small number of patients were studied, so the findings may not be true of other hospital patients.
Dr Jason Oke, senior statistician at the Nuffield Department of Primary Care Health Sciences at the University of Oxford, says: 'It is too early to conclude that hair-loss is an important risk factor for increased severity of Covid-19 infection. Men and women with hair loss should not be overly concerned.'
Am I now permitted to visit my parents on the other side of the country for the weekend?
The short answer is no. The easing of social distancing rules means those who need to leave home to work should do so, but those who are able to work from home should continue to do that.
The Government is still advising us all to limit contact with others – this means not visiting friends or family inside their homes, and not staying overnight away from your own home, except for in a limited set of circumstances, such as for work purposes.
We can spend time outdoors with people we don't live with, in groups of up to six, still adhering to social distancing rules - staying two metres apart.
It's actually against the law to incite others to break these rules, by inviting them to a party, for instance.
You could visit your parents on a day trip and sit in the garden (it's OK to go through the house to access the garden, and go inside to use the loo, but that's it) or a park nearby, though, while sticking to social distancing.