WHAT YOU NEED TO KNOW:
- The clinical trial phase of the leading COVID-19 vaccine candidate has been put on hold after safety concerns were raised.
- The vaccine is being developed by the University of Oxford scientists and drug maker AstraZeneca.
- Phase 3 of the trial was interrupted following a “suspected serious adverse reaction” to the drug in one participant in the UK.
The University of Oxford’s COVID-19 vaccine trials have been put on hold due to safety concerns, pharmaceutical company AstraZeneca announced Tuesday.
“Our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee,” the drug maker said in a statement.
“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 statement continued: “In large trials illnesses will happen by chance but must be independently reviewed to check this carefully.
We are working to expedite the review of the single event to minimize any potential impact on the trial timeline. We are committed to the safety of our participants and the highest standards of conduct in our trials.”
AstraZeneca has been developing the vaccine with the University of Oxford. The phase 3 clinical trials started in the U.S. last week. NBC News has confirmed that the interruption has affected trial sites in the U.S.
According to Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, putting a clinical trial on hold while scientists determine whether a serious adverse effect was caused by a vaccine is rare “but not unheard of.”.
In an email to NBC News, Dr. Gregory Poland, an infectious disease expert and director of the Mayo Clinic’s Vaccine Research Group in Rochester, Minnesota, said “Serious reactions do occur in vaccine trials. Generally, when these events occur, trials are paused, data collected, and an independent data monitoring and safety board reviews the details to make a determination whether to resume the trial or alter it in some way.”
Dr. Offit said that it is likely “we should hear more about what the problem was in a few days.”
Moderna and Pfizer have already begun their phase 3 trials in late July in the US. They have registered roughly 30,000 volunteers. The Oxford vaccine trial was the third phase 3 trial to begin in the country.
The Oxford vaccine uses adenovirus — a type of virus that teaches the immune system how to develop antibodies to attack the coronavirus’ spike protein. The spike protein enables the virus to infect human cells.