Higher levels of von Willebrand factor in hospitalised patient plasma provides an explanation for the association of ABO blood group and secretor status with COVID19 severity. Issue 3 (24th March 2022) - Mankelow, Tosti J.; Blair, Allison; Arnold, David T.; Hamilton, Fergus W.; Gillespie, Kathleen M.; Anstee, David J.; Toye, Ashley M.