AstraZeneca pauses its coronavirus vaccine trial after unexplained illness

AstraZeneca stopped giving shots of its experimental coronavirus vaccine after a person participating in one of the company’s studies got sick, a potential adverse reaction that could delay or derail efforts to speed an immunization against COVID19 for the world.

The pause stemmed from a standard review of the company’s vaccine trials after one person developed an unexplained illness, AstraZeneca said in a statement. The move was intended to give researchers time to examine safety data while maintaining the integrity of the trials, the company said.

The vaccine, which AstraZeneca is developing with researchers from the University of Oxford, has been viewed as one of the leading candidates to reach the market. The decision to tap the brakes jolted investors, sending AstraZeneca’s U. S.- traded shares down sharply, while boosting the stocks of some rivals developing different potential COVID- 19 shots.

“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,” AstraZeneca spokeswoman Michele Meixell said in a statement. She said the company is working to expedite its review of the incident.

The development has the potential to disrupt one of the most closely watched scientific sprints in history. Companies have been working to find a vaccine in hopes of blunting a pandemic that has sickened more than 27 million people and killed over 894,000 worldwide. Health officials in the U. S. and President Donald Trump have repeatedly said that it’s possible to have an immunization before the end of the year, and potentially as early as next month.

The top U. S. official in charge of Operation Warp Speed, the Trump administration’s program to support the rapid development of COVID- 19 vaccines and therapeutics, said experts monitoring the trials in the U. K. paused the late- stage trial in coordination with their U. S. counterparts.

Moncef Slaoui, the head of the Warp Speed initiative, said in a statement that Data Safety Monitoring Boards in the U. S. and U. K. are “conducting an in- depth review of the company’s vaccine candidate which is standard procedure when an adverse event occurs.”

A Data Safety Monitoring Board is a panel of outside experts that watches for potential harm from experimental drugs and vaccines during clinical trials. The bar to pause a vaccine trial is generally low since participants are healthy and may never need the immunization they have volunteered to receive.

The members of the monitoring board have unparalleled insight into clinical studies. Unlike doctors and researchers, they are told whether those participating received the vaccine or a placebo, and they are given regular updates on how each group is faring.

Oxford University’s Jenner Institute didn’t immediately respond to requests for comment.