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Infectious Diseases

Updated 09 April 2020

Some coronavirus deaths caused by extreme reaction from immune system

When fighting coronavirus, the body releases cytokines, which can cause severe symptoms, even when the virus is no longer a threat.

Research has shown that older adults and those with underlying medical conditions are more likely to die from Covid-19 related complications than others.

But what explains the severe symptoms in a number of much younger, seemingly healthy people?

Research published in The Lancet earlier in March 2020 suggested that a subgroup of patients with severe Covid-19 symptoms might suffer these complications, not because of their age or underlying conditions, but a so-called "cytokine storm".

Cytokines are made up of various proteins and are released by the immune cells as a defence response to an intruder, such as a virus. These cytokines have an effect on other cells in the body, which can manifest as inflammation – think of arthritis, as an example – when your immune system is triggered and releases inflammation, manifesting as pain.

The effect of Covid-19 on the immune system

Covid-19 can therefore release a cytokine storm in some patients as their immune systems fight the virus.

These cytokines keep the body on high alert, even long after the viral load of of the Covid-19 virus is no longer a threat. As the cytokines simply do their job, the “fight” results in a severe impact on multiple organs such as the lungs and liver, which can cause deadly complications.

These cytokine storms can happen in people of all ages, but experts believe that this is the reason why so many young people died in earlier pandemics such as the 1918 influenza pandemic. In this pandemic as well, cytokines may offer clues into why younger people can be seriously affected by Covid-19.

Could this make a difference in treatment?

As medical experts suspect complications from cytokine storms in younger patients, it may lead them to adapt treatment. In one such a case, a 42-year-old patient was suffering severe Covid-19 symptoms. Doctors suspected an abundant cytokine release, which lead them to try a drug named tocilizumab, which is used to calm an overactive immune system. After only two doses in the space of eight hours, the patient’s lungs showed signs of improvement.

Understanding the response of the immune system in patients with no underlying conditions might lead doctors to treat severe Covid-19 symptoms as the result of a cytokine storm.

Even though this approach seems very simple, experts say that a cytokine storm isn’t a well-known phenomenon and that many clinicians worldwide need to be made aware of the danger of such an immune response in their patients.

Image credit: Unsplash

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