New Delhi: Shares of drug firm AstraZeneca Pharma, closed over 3 percent lower on Wednesday after the company paused its COVID-19 vaccine study following a participant’s unexplained illness.

The company’s stock had tumbled 13.40 percent to Rs 3,650 during the day on the BSE. It later pared most of the losses closed 3.34 percent lower at Rs 4,074.15. On the NSE, the scrip closed 3.80 percent lower at Rs 4,070. The company’s stock had tanked 12.31 percent to Rs 3,710 during the day.

In a significant development, pharmaceutical company AstraZeneca on Tuesday (September 8) said that it “voluntarily paused” the phase 3 clinical human trials of its vaccine candidate ‘Covishield’ after one of the volunteers got ill. It is to be noted that AstraZeneca is developing this vaccine in collaboration with University of Oxford.

“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 a review of safety data by an independent committee,” the pharma major said in a statement. 

It is learnt that a volunteer developed unexpected sickness during trial of the vaccine for reasons not yet known. AstraZeneca, however, noted that the volunteer would soon recover.

AstraZeneca said it was 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.”

“We are working to expedite the review of the single event to minimize any potential impact on the trial timeline,” the statement added.

Notably, Pune-based Serum Institute of India, which is handling the Phase 3 trials of AstraZeneca’s vaccine in India, is preparing a list of volunteers who will be administered the vaccine shots under the National Immunization Programme (NIP).

It is learnt that 1,600 participants of more than or equal to 18 years of age will be enrolled in the study. Serum Institute of India will conduct the drive on 17 sites in India.