The World Health Organisation has said that the pause on the trials of the Oxford Covid vaccine is a "wake-up call". The world body, however, added that it should not discourage researchers. "This is a wake-up call to recognise that there are ups and downs in clinical development and that we have to be prepared," WHO chief scientist Soumya Swaminathan told a virtual briefing from Geneva. Pharma giant AstraZeneca suspended late-stage trials of vaccine this week after a participant in Britain suffered from neurological symptoms.