Long Covid: 200 symptoms, 145 million affected, no known cause – and no shortage of theories about what triggers the virus hangover

As many as one in five people who get Covid-19 suffer fatigue, breathlessness and brain fog months after their initial infection. Doctors don’t yet know why

Immune system disruption, blood clotting and the continued presence of coronavirus spike protein are possible causes, according to researchers’ theories

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Fatigue, breathlessness and brain fog are among the common symptoms in Covid patients, months after they have recovered. Photo: Shutterstock

Published: 6:15pm, 5 Oct 2022

Millions of people around the world are believed to suffer from long Covid. Although little is known about the condition, recent research has proposed several theories for its cause.

Between 10 and 20 per cent of people who contract the disease are estimated to have long Covid symptoms – most commonly fatigue, breathlessness and a lack of mental clarity dubbed brain fog – months after recovering from the initial infection.

The US-based Institute for Health Metrics and Evaluation (IHME) estimates that nearly 145 million people worldwide had at least one of those symptoms in 2020 and 2021.

In Europe alone, 17 million people had a long Covid symptom at least three months after infection during that time, according to IHME modelling for the World Health Organization (WHO) recently published.

People who had more severe initial cases, including needing to be hospitalised, are more likely to get long Covid, studies suggest. Photo: Shutterstock

These millions “cannot continue to suffer in silence”, WHO Europe director Hans Kluge said, calling for the world to act quickly to learn more about the condition.