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Long covid: What we now know about its causes and possible treatments

Almost four years after the first cases emerged, we are accumulating evidence about the physiology behind this complex condition – from microclots to viral persistence

By Michael Marshall

27 November 2023

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Pete Reynolds

FOR many of us, the covid-19 pandemic is fading into memory. But for millions of people, that isn’t possible as they are still unwell. An illness that is often brief and mild is, for some, the start of a rollercoaster of symptoms that can last years. Today, around 65 million people may have long covid.

That is the bad news. But around four years since the first cases emerged, evidence of the causes of long covid is rapidly accumulating, paving the way for treatments. Multiple trials of therapies are under way and several have already shown promising results. It is now also clear that people experience wide differences in their long covid symptoms, so treating this condition is an exercise in personalised medicine: no single approach will work for everyone.

Many questions remain, however. Can the plummeting levels of certain hormones explain the fatigue and brain fog, and is the persistence of the virus really key to understanding what is going on? And what should we do – and not do – to avoid developing long covid in the first place?

Long covid symptoms

The SARS-CoV-2 coronavirus started spreading around the world in early 2020. Within months, reports began emerging that some people were experiencing lingering symptoms. The term “long covid” was coined in May 2020 and widely adopted. The most common symptoms include headaches, brain fog and fatigue, or post-exertional malaise, in which even small amounts of activity cause exhaustion. Altogether, more than 200 symptoms have been reported, ranging from depression to gastrointestinal problems.

Since…

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