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expert reaction to preprint from the CONVALESCENCE study looking at risk factors for long COVID

A preprint, an unpublished non-peer reviewed study, reports on the latest data from the CONVALESCENCE study at risk factors for long COVID.


Prof Lawrence Young, Virologist and Professor of Molecular Oncology, Warwick Medical School, University of Warwick, said:

“This preliminary study starts to better define the risk factors associated with long COVID.  It supports previous observations that highlight a higher risk of developing long COVID if you are female and if your general health is poor.  While this study helps to improve the characterisation of long COVID, it provides no insights into the mechanisms driving this condition or any interventions that might be of therapeutic benefit.  It is likely that long COVID represents a constellation of different conditions including those usually associated with post-viral fatigue such as chronic fatigue syndrome.  The over-representation of long COVID in women is of particular interest and requires more detailed examination in the context of hormonal factors (e.g. relationship to the menopause, impact of HRT).  Given the long history of the association of persistent virus reactivation with chronic fatigue syndrome, it is also important to determine whether such an effect (e.g. reactivation of Epstein-Barr virus infection) is contributing to long COVID as this would provide opportunities for improved diagnosis and therapy.”


Comment on both this preprint and the REACT-2 preprint on persistent symptoms after self-reported COVID-19 infection, which is under the same embargo:

Dr David Strain, Senior Clinical Lecturer, University of Exeter, said:

“These two separate studies, both tell a similar story – Long COVID is substantially more common than we originally thought, the reported number from the REACT-2 study being around double the number estimated by the ONS report earlier this month.  It is also having a substantial impact on people of all ages with lasting consequences.  Although the risk in the younger population is smaller, it remains significant, which is of concern giving the rising cases of the Delta variant of COVID in the, as yet, unvaccinated under 30s.

“Both of these report on large population samples recruited and identified through different strategies, yet show remarkably similar associations with gender, ethnicity and pre-existing diseases.  This gives vital information beyond simple risk assessments, allowing researchers to start exploring potential mechanisms of the disease in the search for potential treatments or cures.  They also inform clinical service, as the number of long Covid assessment clinics rise beyond 80 across the UK.  If the estimated 2 million, and climbing, sufferers are to be seen within the NHS this will require significant investment into both the education of health care practitioners, who are now treating a condition that did not exist 18 months ago, but also to provide the service in the community and secondary care bases.

“As with all survey or record based studies these both come with the caveat that it is dependent on people with lived experience of the condition reporting their symptoms to their health care practitioner.  It has previously been suggested that this reporting bias may have accounted for some of the ethnic disparities and gender inbalance, however the similar results using two different strategies is highly suggestive that these are true findings.”



Preprint (not a paper): ‘Risk factors for long COVID: analyses of 10 longitudinal studies and electronic health records in the UK’ by Ellen J. Thompson et al. was posted online at 00:01 UK time on Thursday 24 June 2021.  This work is not peer-reviewed.



All our previous output on this subject can be seen at this weblink:



Declared interests

None received.

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