Millions of people who recover from infections like COVID-19, influenza and glandular fever are affected by long-lasting symptoms. These include chronic fatigue, brain fog, exercise intolerance, dizziness, muscle or joint pain and gut problems. And many of these symptoms worsen after exercise, a phenomenon known as post-exertional malaise.
Medically the symptoms are known as myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS). The World Health Organization classifies this as a post viral fatigue syndrome, and it is recognised by both the WHO and the United States Centers for Disease Control and Prevention as a brain disorder.
Experiencing illness long after contracting an infection is not new, as patients have reported these symptoms for decades. But COVID-19 has amplified the problem worldwide. Nearly half of people with ongoing post-COVID symptoms – a condition known as long-COVID – now meet the criteria for ME/CFS. Since the start of the pandemic in 2020, it is estimated that more than 400 million people have developed long-COVID.
