Coronavirus: Obese higher risk as fat cells are infection targets
The reason why obese people may be more at risk of dying from coronavirus could be because their fat cells make large amounts of a protein used by the infection to infiltrate human cells.
The coronavirus – scientifically called SARS-CoV-2 – latches onto ACE-2 receptors, known as the ‘gateway’ into cells inside body.
Fat cells express ACE-2 receptors, which experts say may explain why obese people have higher odds of suffering a severe bout of COVID-19.
ACE-2 is also expressed in the fat cells of people with type 2 diabetes – another high-risk health condition driven by obesity.
Some researchers now believe diabetes drugs could be used to fight the infection – and admitted that losing weight may also have a benefit.
The scientists who posed the theory, from Germany and the US, also outlined how fat cells are linked to a lung-scarring condition called pulmonary fibrosis.
With COVID-19 added on top, the lungs would struggle to get enough oxygen to the rest of the body.
The evidence is not concrete but data from hospitalised COVID-19 patients suggests obese people are more likely to die than those who are slim.
Public Health England has launched an investigation into how obesity plays a role in disease severity, as well as ethnicity and gender.
The coronavirus – scientifically called SARS-CoV-2 – latches onto ACE-2 receptors, known as the ‘gateway’ into cells inside body. Fat cells ‘widely express’ ACE-2 receptors, which may explain the link between obesity and severe COVID-19
The evidence is not concrete but data from hospitalised COVID-19 patients suggests obese people are more likely to die than those who are slim
Dr Ilja Kruglikov of Wellcomet GmbH in Germany, wrote ACE-2 is ‘widely expressed’ in fat cells called adipocytes (pictured) in obese people and type 2 diabetics
Researchers at New York University recently highlighted obesity as a main driver of patients under the age of 60 needing hospital care. The team found those with a BMI between 30 and 34 were almost twice as likely to be admitted to acute or critical (ICU) care than those with a BMI under 30. This likelihood increased to 3.6 times in those patients with a BMI of 35 or more
Around three in ten adults in England are clinically obese – a Body Mass Index above 30. The rate is among the highest in the Western world.
According to data from NHS hospitals, 75 per cent of COVID-19 patients in intensive care are overweight, compared with 65 per cent in the general population.
In a ‘perspective’ paper published in the journal Obesity, the researchers explained the link between obesity and COVID-19 that has emerged.
Angiotensin-converting enzyme 2 (ACE-2) is the entry point for the virus. Its spiky surface binds to the receptors and, from there, replicates.
Dr Ilja Kruglikov of Wellcomet GmbH in Germany, wrote ACE-2 is ‘widely expressed’ in fat cells called adipocytes in obese people and type 2 diabetics.
Fat might therefore ‘serve as a viral reservoir’, warned Dr Kruglikov and his colleague Philipp Scherer of the University of Texas Southwestern Medical Center, Dallas.
The scientists also explained that fat cells may drive the production of a type of cell called myofibroblasts.
Myofibroblasts are a major driver of pulmonary fibrosis – scarring of the lung tissue which reduces the organs function and oxygen intake.
Infected patients have been found to have pulmonary fibrosis in their lungs, but it was likely already present before they became ill.
According to a report on intensive care patients in the UK, people of a healthy weight make up a minority of critically ill COVID-19 patients. Almost three quarters are carrying extra weight (BMI of 25 to 40+)
ACE-2 receptors are the entry point for the coronavirus into cells, scientists say
WHAT IS THE EVIDENCE THAT OBESITY IS A RISK FACTOR FOR COVID-19?
There have been no studies which clearly mark the largest risk factors for COVID-19 – the disease caused by SARS-CoV-2.
But, using data from hospitals, researchers are able to identify which conditions are common among those who are frequently in hospital with the disease.
One study in New York City, the world’s coronavirus hotspot, found obese people were more likely to be hospitalised with the coronavirus than cancer or lung disease patients who have compromised immune systems.
The ‘surprising’ findings also showed that even smoking wasn’t a predictor of hospitalisation like obesity was, despite the habit being bad for the lungs.
The researchers at the NYU Grossman School of Medicine, who analysed hospital reports of 4,103 COVID-19 positive patients, found is that ‘in the decision tree for admission, the most important features were being over 65 and obesity.’
Researchers at New York University recently highlighted obesity as a main driver of patients under the age of 60 needing hospital care.
They looked at the records of 3,615 patients who tested positive between March 4 and April 4.
The team found those with a BMI between 30 and 34 were almost twice as likely to be admitted to acute or critical (ICU) care than those with a BMI under 30.
This likelihood increased to 3.6 times in those patients with a BMI of 35 or greater, according to the findings published in Clinical Infectious Diseases.
In patients over 60 years, the researchers didn’t find a significant link between obesity and severe illness that needed critical care.
One study by US health officials, which recorded the weights of 178 patients, found obesity was the most common underlying condition for patients aged under 65 who were admitted to hospital for COVID-19.
Of those aged between 18 and 49 who had a health condition, obesity accounted for 60 per cent. The second most common condition was asthma, at 27 per cent.
For those between 50 and 64 years of age with an underlying health problem, obesity accounted for 49 per cent – more than the 47 per cent who had high blood pressure.
Comparatively, according to data from the UK’s National Health and Nutrition Examination Survey, age-adjusted obesity prevalence is 42 per cent.
In the UK, according to data from hospitals, almost 75 per cent of COVID-19 patients in intensive care are overweight, compared with 65 per cent in the general population.
And NHS data last week revealed obesity raises the risk of dying from coronavirus in hospital by nearly 40 per cent.
The analysis of 17,000 COVID-19 admissions found death rates were 37 per cent higher among obese patients, second only to dementia (39 per cent) but more than heart disease (31 per cent).
The research was conducted by a team of Britain’s top infectious diseases scientists who are part of the pandemic-planning global body.
The risk of pulmonary fibrosis, which develops over time, increases with age. It is especially high in people over the age of 65.
The scar tissue can destroy the normal workings of the lungs and make it hard for oxygen to get into the blood, causing shortness of breath.
The presence of pulmonary fibrosis is ‘likely to influence the clinical severity of COVID-19’, the scientists said.
To combat this, the researchers urged for a ‘probe’ into drugs called TZDs, or ‘glitazones’, which are taken by diabetics to manage glucose levels.
TZDs could ‘have the potential to restore a higher degree of functionality in lung tissue’ by stabilising the production of myofibroblasts.
However, a big concern is that TZDs have side effects of weight gain and heart effects. Therefore, they should be given only when COVID-19 symptoms become clear, the authors wrote.
Metformin, another diabetic drug, has also been shown to resolve pulmonary fibrosis in laboratory studies.
Whether TZDs and metformin can reduce ACE-2 expression in fat cells and influence the severity of SARS-CoV should be investigated, the academics said.
Ian Hall, professor of molecular medicine, University of Nottingham, said there is ‘no evidence’ TZDs could help cut the risk of infection but admitted it is plausible.
He told The Times: ‘One challenge we have is that there are multiple suggestions of drugs which could work in COVID-19 based on hypotheses which are credible, but it takes time to assess all of these properly.
‘The virus enters through the respiratory tract, so it is the level of expression of ACE-2 in the respiratory tract which is likely to be most important in early stages of infection.’
Professor Scherer said people with obesity should be extra stringent to prevent catching the coronavirus.
He said: ‘Individuals with obesity at the upper end of the spectrum fall into a high-risk category at multiple levels and should exercise additional caution not to expose themselves.’
The paper concluded: ‘In addition, since obesity is such a major risk factor for a negative clinical prognosis, weight loss per se is a viable strategy as well, even though this is clearly hard to achieve in the absence of any pharmacological interventions.’
It comes as the government said an inquiry into which people were most affected by Covid-19 would consider obesity as a factor.
Matt Hancock has ordered health officials to trawl through the records of thousands of pandemic victims to understand why some people are more affected by the disease than others.
The Health Secretary said at the daily news conference on May 4: ‘Emerging data from around the world suggests there could possibly be a relationship between obesity and the impact of Covid-19 on individuals.
‘It’s too early to say if obesity in itself is a factor or conditions associated with it – or there is not enough data yet to rule it out – so we need to approach any assumptions with caution.
‘As part of our continued effort to understand even more about Covid-19, we have commissioned work from Public Health England to consider the impact of various factors such as ethnicity, obesity, age, gender and geographical location and how these may have an impact on someone’s susceptibility to the virus.’
The Government hopes to publish the findings at the end of this month and they will be used to decide whether ‘further action’ should be taken to protect these groups.
This could include extra social distancing precautions or special advice for NHS staff on the front line who are deemed at risk.
Researchers at the University of Liverpool warned last week that obesity increased the risk of dying from the virus by 37 per cent.
After analysing of 17,000 COVID-19 admissions, they found death rates were 37 per cent higher among obese patients, second only to dementia (39 per cent) but more than heart disease (31 per cent).
SARAH VINE: Who’ll dare to face the facts on obesity and Covid-19?
With each day that passes, with each new grim death toll, we learn a little bit more about the nature of this ghastly virus.
This week in particular, statistics have come to light showing that obesity is emerging as one of the biggest risk factors for Covid-19.
According to data released by the NHS, being overweight raises the chances of dying in hospital from the illness by 40 per cent.
Having a body mass index of between 30 and 34 makes a person almost twice as likely to be admitted to ICU as someone with a BMI under 30. For those with a BMI of 35 or more, the likelihood is nearly four times higher.
This is a very tricky piece of information for the Government to handle. Obesity is a highly politicised issue: ‘fat-shaming’ is one of the more heinous crimes against political correctness.
The notion that the medical establishment is acutely aware of the newly discovered risks of obesity, yet fearful of talking about it, was reinforced by a conversation I had last week with a friend who is a leading bariatric surgeon.
Obesity is emerging as one of the biggest risk factors for the coronavirus pandemic
Can you imagine if Matt Hancock asked people struggling with obesity to shield themselves and social distance from the virus like he has done with the over-70s?
‘It’s a very difficult subject to broach,’ he told me, ‘and no one quite wants to say it, but there’s no question in the mind of any of my colleagues: patient size is a major factor in this disease.’
As the UK has the highest proportion of seriously overweight people in Europe, this is of grave concern. Yesterday, an NHS report said 67 per cent of men and 60 per cent of women here are overweight or obese.
It means that as a population in general, we are inherently more at risk of dying from coronavirus.
Yet persuading people to accept that their weight can be a major health issue is very hard indeed.
That is because size is deeply bound up in psychological issues and self-esteem. Fat people, as I know from a lifetime’s struggle with the scales myself, can be very defensive about their condition. We interpret any concern about our weight as negative criticism, an attack on our identities.
Big people — and in particular bigger women — have become so sacred that none but the most bigoted would dare criticise.
I know how joyless life can be when you feel — as so many do — that your only friend is the tub of ice cream in the freezer. That is why I’ve always felt that obesity was in effect an eating disorder that needs to be managed as much in the mind as in the body.
For any politician — especially a lean male such as Health Secretary Matt Hancock — to have to step into this minefield is tough. It’s hard enough having to ask the over-70s to shield themselves; can you imagine the hysteria if he asked the obese to do the same? Or suggested that people should isolate according to their weight, rather than their age?
But if the science is correct, maybe that should be the strategy.
Because there is one fundamental difference between the obese and the over-70s. Age is not a choice. Size, ultimately, is.
For the past six weeks, the nation has talked of nothing else but ‘saving our NHS’. Yet for a decade we have been bringing the NHS to its knees by refusing to take personal responsibility for obesity.
It puts us at increased risk of developing cancers, high blood pressure and type-2 diabetes — conditions that cost the health service billions of pounds a year.
So if we really want to protect the NHS, those of us who are overweight or obese can start by taking a deep breath, stepping on those scales and beginning the long, hard journey back to health.
The virus may be tailing off now but a second wave is expected in the winter. There are a good few months between now and then.
If you can be inspired to lose weight, you might not only help to save the NHS. You might just be saving yourself.
WHY MIGHT OBESE PEOPLE MORE AT RISK OF BECOMING VERY ILL FROM COVID-19?
Studies have shown obese people are more likely to suffer serious complications or die from infections, such as the flu.
Doctors say the immune systems of fat people are constantly ramped up as they try to protect and repair the damage inflammation causes to cells.
Using all its energy fending off inflammation means the body’s defence system has few resources left to defend against a new infection like COVID-19.
Dr Dyan Sellayah, a lecturer in cellular and organismal metabolism, University of Reading, said obese people tend to have dysfunctional immune systems.
‘Their fat tissue for example becomes a reservoir for immune cells known as macrophages. While these cells reside in our fat under normal circumstances, in obesity they are at higher frequency and become more troublesome (they start to secrete inflammatory cytokines) and negatively impact on immune and metabolic health.’
Obese people might eat a diet with very little fiber and antioxidants – which keep the immune system healthy – such as fruit and vegetables.
Most patients with a BMI of over 40 suffer from breathing problems that range from simple shortness of breath to a potentially life-threatening condition known as obesity hypoventilation syndrome (OHS).
Excess weight also makes it more difficult for the diaphragm and lungs to expand and inhale oxygen. Starved of oxygen, organs will begin to fail.
These factors may explain why obese people’s lungs tend to fail faster when the new coronavirus strikes, compared to a healthy person.
COVID-19 kills by spreading deep into the lungs and causing complications such as pneumonia.
There are several other factors that may increase an obese person’s chance of falling seriously ill with coronavirus, including a lack of exercise.
Studies have shown that physical activity increases the numbers of certain immune cells that help to bolster immune activity.
Clogged up arteries also make it hard for blood carrying immune cells to pass through and repair cells around the body.