The clinical trial of one of the world’s most promising coronavirus vaccines has been put on hold due to an unspecified safety issue. The research behind the so-called Oxford Vaccine originated from Oxford University, and scientists there have partnered with pharmaceutical giant AstraZeneca to conduct the large-scale randomized and controlled trials needed for a shot that would, if deemed safe, be administered to hundreds of millions. The drug entered phase three of its clinical trial—human testing conducted on volunteers—last week. AstraZeneca said in a statement, “Our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee. 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.” Drugmakers recently signed a pledge to abide by the safety standards for medical manufacturers amid questions about White House pressure to deliver a COVID-19 vaccine by election day.