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Four things we’ve learned about Long Covid

In the 10 months since COVID-19 entered the world stage, our knowledge of the disease has grown every single day. Latest figures state that over 34 million cases have been diagnosed around globally – with just over 23 million of those reported having recovered.

For some people, recovery hasn’t come after a few weeks of feeling mildly ill. And though they were infected months ago, they are still suffering from a wide variety of symptoms – many which aren’t related to the common indications we’ve been told to look out for today.

These people with “Long Covid” number in the tens of thousands in the UK and include Inside Science presenter Dr Adam Rutherford, who was diagnosed with the virus in mid-March but still feels its effects today. Over several weeks, Adam’s explored the science behind the phenomenon, speaking to experts and other “long-haulers” to find out more for Long Covid on BBC Radio 4.

In that time, writes Dr Alex Lathbridge, here are four things that we’ve learnt about the lasting effects of Covid-19.

Conceptual illustration of coronavirus spreading. Image source: Getty Images

It’s not all about the lungs

With notable symptoms being fatigue and shortness of breath, Covid-19 is primarily considered to be a respiratory illness. However, long-haulers are experiencing a wide variety of symptoms associated with multiple organs – ranging from problems with memory to gastrointestinal issues.

It’s not just the spectrum of symptoms – it’s also about understanding the root of it in the body. One common symptom described by long-haulers is “chest-heaviness”. Though its root cause might seem obvious as something lung-related, experts are not sure if this is a respiratory illness, a cardiovascular issue or if it’s muscular in origin.

There might be a storm brewing

For some patients with Covid-19, their immune systems can become their own worst enemy.

The immune system is incredibly complex, yet its main role is simple: protect the body. When it responds to a virus like SARS-CoV-2, immune cells communicate with one another using a type of small protein known as a cytokine. When the virus enters and damages the lungs, these messengers help co-ordinate the immune cells moving to the organ to engage the virus – leading to a small amount of inflammation in the area.

But it’s all about magnitude. If the immune system overreacts, immune cells are triggered to overproduce cytokines. These then signal the production of even more immune cells and positive-feedback cycle continues into something known as a “cytokine storm” (associated with Covid-19 and other outbreaks, like SARS, MERS, and “bird flu” – the H5N1 influenza virus). These messengers spill out into the bloodstream and the scale of the immune response can have fatal repercussions in the form of multi-organ failure.

If the immune system overreacts, immune cells are triggered to overproduce cytokines. These then signal the production of even more immune cells and positive-feedback cycle continues into something known as a “cytokine storm”

Some researchers think that cytokine storms might be one part of the puzzle in explaining some of the different experiences – why some people have relatively mild symptoms while others’ are more severe. But it’s not just the physical problems that patients are having to deal with...

It can get into your head

Mental health problems such as anxiety are common after viral infections like Covid-19, according to experts. Some researchers have been looking into the idea that many of these psychiatric and neurological conditions reported might be down to biology.

When cytokines are migrating through the bloodstream, they weaken the blood vessels (allowing them to enter your other organs). One of those is the blood-brain barrier – specialised cells lining the brain and spinal cord that prevent microbes and other agents from infecting the brain.

Considering that the brain has receptors on it that the virus binds to, there’s growing evidence that the virus directly damages the brain.

It’s not just the biology that’s impacting mental health. No matter if you’re watching TV, scrolling on your phone or listening to the radio, Covid-19 is on everyone’s lips. For people who’ve had the illness and are one of the “long-haulers”, this 24/7 reminder is just one of the things that can contribute to their anxiety. Combining this with anxieties about their symptoms, experiences of being hospitalised, and the fear of re-infection means that the mental impact of the disease will have to be treated seriously if a full recovery is to happen.

There’s still a long way to go…

We still lack many pieces required to solve the puzzle that is Covid-19. Though the science may still be in its infancy, healthcare systems are constantly adapting to the new challenges posed by the virus. Ways of remotely diagnosing people are being developed, with the idea that methods like self-reported questionnaires can aid doctors in directing people with suspected Covid-19 to the correct services.

Researchers now know that it’s time to expand how we look at the data around the outbreak. Constantly updating statistics of confirmed cases vs confirmed recoveries can miss the fine details of the ever-changing landscape. Now that we’re encountering more stories of those who’ve fallen through the statistical gap and haven’t fully recovered 6 months after being infected, how we tease the data apart will decide how countries across the globe fight against the disease.

You can find out more about the science by listening to Long Covid on Scientifically…

Dr Alex Lathbridge is a biochemist and computational biologist

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