British pharmaceutical giant AstraZeneca has halted the clinical trial of its much awaited coronavirus vaccine after a volunteer developed ‘unexplained illness’, CNN reported on Wednesday. The drug company, which is developing the vaccine alongside University of Oxford, in a statement, described the event as ‘routine action’.

“As part of the ongoing randomized, controlled global trials of the Oxford coronavirus vaccine, our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee,” a spokesperson said.

“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 spokesperson added.

Also Read: First batch of Sputnik V vaccine for civilian circulation produced in Russia: Reports

AstraZeneca is considered to be the frontrunner in the race for vaccine against the coronavirus which has infected 27,722,275 people so far. The death toll stands at 900,878, as per the worldometers data.

The drug company is among the nine firms which are currently in Phase 3 trials for their vaccine candidates. AstraZeneca reportedly enrolled 30,000 volunteers in the US for the vaccine trials.

The vaccine, called AZD1222, uses a weakened version of a common cold causing adenovirus that has been engineered to code for the spike protein that the novel coronavirus uses to invade cells, AFP reported.