The hospitalised patients were arranged into mild, moderate and severe disease based on their oxygen requirements.
Patients on acute non-invasive ventilation, invasive ventilation and admission to intensive care automatically led to classifying patients as having severe disease.
Healthy blood samples were obtained from frontline workers at the University of Manchester and Manchester University NHS Foundation Trust (MFT) and examined alongside patient samples.
At outpatient review, patients undertook rigorous questionnaires which assessed whether they had increased levels of breathlessness and/or fatigue, and if this was new since SARS-Cov-2 infection.
Unique monocyte profiles distinguished long COVID patients with shortness of breath and unresolved lung injury from those with ongoing fatigue, and from asymptomatic patients.
The study was funded by The Wellcome Trust, the Royal Society, The Medical Research Council, The Kennedy Trust for Rheumatology Research, The Lister Institute, BBSRC and UKRI
Dr Elizabeth Mann, Wellcome Trust/Royal Society Sir Henry Dale Fellow at The University of Manchester’s Lydia Becker Institute said: “There is now a wealth of evidence indicating that chronic morbidity persists in many COVID-19 patients during convalescence manifesting as long COVID which remains a global public health problem despite vaccination programmes and milder strains of SARS-CoV-2.
“These debilitating symptoms including extreme fatigue, shortness of breath, myalgia, brain fog, depression, fibrotic lung disease and pulmonary vascular disease and we now know this can last for many months or even years following infection.
“But treatment options for long COVID are currently limited, since the development of targeted therapeutic strategies requires an in depth understanding of the underlying immunological pathophysiology.
“Our work finding a link between monocyte function and specific long COVID symptoms may provide an important first step on the road to possible treatments.”
Professor of Inflammatory Disease, Tracy Hussell is Programme Lead in the Next Generation Phenotyping and Diagnostics Theme at NIHR Manchester BRC and Director of the Lydia Becker Institute at The University of manchester
She added: “This study, led by Dr Mann's team, is a prime example of the ‘one Manchester’ approach that provides seamless integration between clinicians and scientists under the umbrella of our NIHR Biomedical Research Centre and the generosity of our patient population.”
The paper Monocyte migration profiles define disease severity in acute COVID-19 and unique features of long COVID is published in the European Respiratory Journal here.
