- The United Kingdom's Medicines Health Regulatory Authority that it was safe to resume clinical trials after a brief pause.
- AstraZeneca paused trials earlier this week due to a potentially unexplained illness.
- CEO Pascal Soriot said during a private conference call that the illness occurred in a woman in the U.K. who displayed neurological symptoms consistent with a spinal inflammatory disorder called transverse myelitis.
- Illnesses often occur by chance in large trials but are investigated out of an abundance of caution.
Phase three trials for AstraZeneca's coronavirus vaccine have resumed in the U.K. after they were halted earlier this week over safety concerns, raising hope that one of the leading candidates in the global race to develop an injection which can stem the pandemic is back on track.
AstraZeneca said it received confirmation from the United Kingdom's Medicines Health Regulatory Authority that it was safe to resume clinical trials. The company declined to disclose medical information about the pause of the trial, but indicated earlier this week that a potentially unexplained illness was under investigation.
The company said "the standard review process triggered a voluntary pause" to all global trials on Sept. 6 so that independent committees and internal regulators could review the safety data. While trials can now resume in the U.K., the status of trials elsewhere remains unclear.
"The Company will continue to work with health authorities across the world and be guided as to when other clinical trials can resume to provide the vaccine broadly, equitably and at no profit during this pandemic," AstraZeneca said in a statement.
The University of Oxford, which developed the vaccine in partnership with AstraZeneca, said Saturday that some 18,000 people have so far received the vaccination in trials.
"In large trials such as this, it is expected that some participants will become unwell and every case must be carefully evaluated to ensure careful assessment of safety," Oxford said in a statement.
STAT News reported earlier this week that AstraZeneca's CEO Pascal Soriot said during a private conference call that the "potentially unexplained illness" occurred in a woman in the U.K. who displayed neurological symptoms consistent with a spinal inflammatory disorder called transverse myelitis. The call was set up by investment bank J.P. Morgan, STAT reported.
On the same call, Soriot also confirmed that AstraZeneca's clinical trials had been halted once before in July after a participant experienced neurological symptoms, but the illness was found to be unrelated to the experimental vaccine.
AstraZeneca's potential coronavirus vaccine, called AZD1222, is among the frontrunners in the race toward a safe and effective vaccine that could put a dent in the global pandemic. The company launched its late-stage trials at the end of August. It's one of at least three vaccine candidates, along with Pfizer's and Moderna's, in late-stage trials.
Officials from the World Health Organization have previous hailed AstraZeneca's vaccine candidate as one of the most promising currently in development. On Thursday, WHO Chief Scientist Dr. Soumya Swaminathan said there's no need to be "overly discouraged" by the news of the pause of the trial, adding that "these things happen."
"I think this is a good ... perhaps a wake-up call or a lesson for everyone to recognize the fact that there are ups and downs in research, there are ups and downs in clinical development and we have to be prepared for those," she said.
The United States has invested more than $10 billion in six efforts to bring a coronavirus vaccine to market. On May 21, the U.S. announced it would invest $1.2 billion in AstraZeneca's effort in exchange for at least 300 million doses if the candidate proves safe and effective enough.