Calm before the cytokine storm: Deadly immune overreaction killing many coronavirus patients cruelly strikes AFTER people start to feel better, top doctor claims
- The coronavirus can trigger immune molecules known as cytokines in excess
- It causes widespread tissue damage, resulting in multi-organ failure and death
- Professor David Isenberg said there is often a ‘lull before the storm’
- Patients can appear to be recovering before the deadly complication
The deadly immune overreaction killing many coronavirus patients strikes after people start to feel better, a top doctor has claimed.
In some people – particularly the elderly and those with underlying health conditions – their immune systems go haywire while trying to clear Covid-19 in the body.
Known as a ‘cytokine storm’, the deadly complication sees immune molecules start to attack healthy tissue as well, including vital organs such as the heart and lungs.
Professor David Isenberg, director of the University College of London Centre for Rheumatology, said there is often a cruel ‘lull before the storm’, whereby a patient may seem to be recovering before the fatal reaction.
Professor Isenberg said it still remains a ‘mystery’ which patients are vulnerable to suffering the life-threatening complication.
The cytokine storm that kills critically ill Covid-19 patients strikes after the patient start to feel better, a top doctor has revealed. Pictured: A patient in ICU at Whiston Hospital in Merseyside, October 20
A cytokine storm appears to be one of the common causes of mortality in the the Covid-19 pandemic, inflicting damage on the heart, liver and kidneys.
Abnormal blood clotting, causing heart attack and stroke, has also been highlighted as a significant cause of death in Covid-19 patients.
Devastating lung inflammation triggered by the so-called ‘cytokine storm’ is thought to be what ultimately kills the sickest coronavirus patients.
Cytokines are a group of cells involved in the immune system’s response to injury or infection.
They race to the site of a problem and signal to the body to send more immune cells to mount a defense against a foreign invader.
It’s a crucial part of how the body heals itself – but when it goes haywire it can lead to devastating damage.
The influx of immune cells causes inflammation which, when persistent, an go awry and start killing cells in the very tissues the immune system is trying to protect
When overabundant signalling cytokine cells stay switched ‘on’ for too long inflammation can continue out of control.
This inflammation overwhelms the lungs of coronavirus patients, sending them into respiratory failure an ultimately killing many of them if this inflammation can’t be stemmed.
There is not a clear figure for the proportion of hospitalised patients who experience the cytokine storm.
One paper in the Journal of Internal Medicine said a lack of white blood cells, a component of the cytokine storm, ‘is one of the most prominent characteristics of Covid-19’.
Professor Isenberg, speaking at a virtual Royal Society of Medicine webinar, said: ‘You may see what seems to be an improvement after a short while either spontaneously or due to therapy.
‘But it’s a lull before the storm because having improved somewhat, it can then come back again and that’s when it can be truly fatal.’
In terms of when it starts, ‘it seems to be about two weeks’ after initial infection, Professor Isenberg said.
He added: ‘Cytokines are small molecules. They are part of body’s innate response to infection but a sudden release in large amounts is what causes problems.
‘The storm is when the innate immune system gives rise, to reasons which are still not entirely clear, to a completely uncontrolled and excessive release in these pro-inflammatory signally molecules.
‘We see a whole variety of consequences of this. This is not specific to Covid, we have seen this before going right back to the influenza pandemic in 1918 and 1919, which is thought to be responsible incidentally for deaths disproportionate number of deaths in younger people.’
Professor Isenberg said ten months into the Covid-19 crisis, it was still not clear which type of patients were most likely to suffer the deadly complication.
He said: ‘What still remains a bit of a mystery is why some individuals are more prone to the problem than others.’
There is only one drug, dexamethasone – a cheap £5 steroid – that has been proven to inhibit the cytokine storm. It works by dulling the immune system during infection, essentially protecting it from itself.
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