OxCOVID19 Database, a multimodal data repository for better understanding the global impact of COVID-19 by Mahdi, A, Błaszczyk, P, Dłotko, P, Salvi, D, Chan, T-S, Harvey, J, Gurnari, D, Wu, Y, Farhat, A, Hellmer, N, Zarebski, A, Hogan, B, Tarassenko, L