Coronavirus can cause hundreds of deadly blood clots in the lungs, new study finds

Patients with severe cases of Covid-19 had abnormal blood clotting which contributed to some deaths, research has found.

The study found that patients with higher levels of blood clotting had a significantly worse prognosis and were more likely to require intensive care.

Scientists from the Royal College of Surgeons in Ireland (RCSI) said their findings show Covid-19 is associated with a unique type of blood clotting.

The study, carried out by the RCSI's Irish Centre for Vascular Biology (ICVB) and St James's Hospital, Dublin, has been published in the British Journal of Haematology.

The authors found that abnormal blood clotting occurred in patients with severe Covid-19 infection, causing micro-clots in the lungs.

Professor James O'Donnell, director of the ICVB said: 

Our novel findings demonstrate that Covid-19 is associated with a unique type of blood-clotting disorder that is primarily focused within the lungs and which undoubtedly contributes to the high levels of mortality being seen in patients with Covid-19.

Prof O'Donnell, a consultant haematologist with the National Coagulation Centre at St James's Hospital, said this scenario is not seen with other types of lung infection.

In addition to pneumonia affecting the small air sacs within the lungs, we are also finding hundreds of small blood clots throughout the lungs, he added.

This explains why blood oxygen levels fall dramatically in severe Covid-19 infection. Understanding how these micro-clots are being formed within the lung is critical so that we can develop more effective treatments for our patients, particularly those in high risk groups. Further studies will be required to investigate whether different blood-thinning treatments may have a role in selected high-risk patients in order to reduce the risk of clot formation.

Emerging evidence also shows that the abnormal blood-clotting problem in Covid-19 results in a significantly increased risk of heart attacks and strokes.

Prof O'Donnell led the cross-disciplinary study, with joint first authors Dr Helen Fogarty and Dr Liam Townsend, along with consultants from multiple specialities at St James's Hospital and researchers at RCSI University of Medicine and Health Sciences and Trinity College Dublin.

Further research will continue under the Irish Covid-19 Vasculopathy Study, which has been jointly funded by the Health Research Board and Irish Research Council as part of the Irish Government's Covid-19 Rapid Response Research funding.