As part of the ongoing clinical trials of the AstraZeneca Oxford coronavirus vaccine, AZD1222, a standard review process has been triggered, resulting in the voluntary pause of vaccination across all trials to allow an independent committee to review the safety data of a single event of an unexplained illness that occurred in the UK Phase III trial. This routine action happens whenever there is a potentially unexplained illness in one of the trials. In large clinical trials, illnesses must b...