The study, led by scientists from University College London (UCL), is the largest peer-reviewed research into long Covid, studying the responses of 3,762 eligible participants from 56 countries.
The study found that the most common symptoms of long Covid ranged from fatigue, post-exertional malaise to hallucinations, tremors and tinnitus. Other symptoms noticed were itchy skin, changes in the menstrual cycle, sexual dysfunction, heart palpitations, memory loss, blurred vision, and diarrhoea.
The researchers created a web-based survey which was designed to characterise the symptoms and time course in patients were confirmed or suspected to have long Covid.
The symptoms were identified in 10 organ systems, out of which one-third continued to affect patients for at least six months. A total of 2,454 respondents had symptoms lasting longer than six months and they experienced an average of 55.9 symptoms, across an average of 9.1 organ systems. The study also said that the patients experienced an average of 13.8 symptoms during the seventh month.
Athena Akrami, a neuroscientist at University College London (UCL) and senior author of the study, was quoted by The Guardian as saying, “This is important for medical researchers who are looking for the underlying [disease mechanisms], and also for doctors that provide care and treatment because it suggests they should not just be focusing on one organ system.”
The researchers of the study called for widening the clinical guidelines for assessing patients with long Covid apart, from the currently advised cardiovascular and respiratory function tests. They said that the assessment should include neuropsychiatric, neurological, and activity intolerance symptoms.
Akrami, who was still experiencing symptoms 16 months after getting infected by the virus added, “There are likely to be tens of thousands of long Covid patients suffering in silence, unsure that their symptoms are connected to Covid-19.”
However, the researchers also acknowledged several limitations to the study, including how it exposes the possibility of recall bias and sampling bias towards long Covid patients who joined support groups and were active participants of the groups at the time the survey was published.