AstraZeneca halts Covid-19 vaccine trials to assess safety issue - POLITICO

"This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials," the company said in a statement. https://www.politico.com/news/2020/09/08/astrazeneca-halts-covid-19-vaccine-trials-410308