The presence of more than five symptoms of Covid-19 in the first week of infection is significantly associated with the development of long Covid, irrespective of age or gender, according to a new study.
For the study, researchers from the University of Birmingham conducted a review that examined long Covid symptoms such as fatigue, shortness of breath, muscle pain, cough, headache, joint pain, chest pain, altered smell, diarrhoea and altered taste.
The team identified two main symptom clusters of long Covid: those comprising exclusively of fatigue, headache and upper respiratory complaints; and those with multi-system complaints including ongoing fever and gastroenterological symptoms.
The findings are published in the Journal of the Royal Society of Medicine.
"There is evidence that the impact of acute Covid-19 on patients, regardless of severity, extends beyond hospitalisation in the most severe cases, to ongoing impaired quality of life, mental health and employment issues," said lead author Olalekan Lee Aiyegbusi, Deputy Director at the University's Centre for Patient Reported Outcomes Research.
"More than one-third of the patients in one of the studies included in the review reported they still felt ill or in a worse clinical condition at eight weeks than at the onset of Covid-19," Aiyegbusi added.
In a comparison with other coronaviruses, the researchers suggest that in the longer term, patients with long Covid may also experience a similar disease trajectory to that of patients who had SARS or MERS, pointing to analysis showing that six months after hospital discharge, approximately 25 per cent of patients hospitalised with SARS and MERS had reduced lung function and exercise capacity.
"Neither the biological or immunological mechanisms of long Covid, nor the rationale for why certain people are more susceptible to these effects, are yet clear, limiting development of therapies. It is essential we act quickly to address these issues," said Shamil Haroon, Clinical Lecturer in Primary Care and co-Principal Investigator in the study.