Celebrations to ring in 2021 were subdued in many parts of the world as traditional gatherings were cancelled to help stem the rising number of cases of COVID-19. The new, more transmissible, variants of the virus are causing pressure on health-care systems around the world and, although the positive results from numerous vaccine trials announced at the end of the year seemed to offer a glimmer of hope, it is clear now that there will be many more deaths before the disease is brought under control.
What has been heartening is the speed at which research into COVID-19 has been undertaken. In the past year, over 1500 articles on COVID-19 and thrombosis have been published. Since our editorial last June, there have been some answers to the question of what role thrombosis plays in the severity of COVID-19. Early observational studies indicated that anticoagulation therapy was associated with improved outcomes for patients with severe disease. However, new evidence from the REMAP-CAP randomised controlled trial indicates that for patients with severe disease who required intensive care unit (ICU) support, therapeutic anticoagulation drugs did not improve outcomes and increased bleeding risk. The enrolment of these patients into the trial has been stopped, along with those in the ACTIV-4 and ATTACC trials, although patients who do not require ICU care at the time of enrolment will continue to be enrolled.
It is clear that there is still much to be learnt regarding thrombosis and COVID-19. To help facilitate this research, guidelines have been developed by the International Society of Haemostasis and Thrombosis and the American Society of Hematology to help clinicians to report clotting and bleeding events associated with COVID-19 in a uniform manner. It is hoped that standardising reporting will lead to more opportunities to compare and pool data, which will be necessary to determine how best to treat patients with COVID-19 of different degrees of severity, and to determine whether the thrombosis seen is a direct consequence of infection with the virus or is a result of the inflammatory response.
For the observational study see J Thromb Haemost 2020; 18: 1094–99
For the thrombosis and COVID-19 toolkit see Blood Adv 2020; 4: 6259–73
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