Phase III COVID-19 vaccine trial halted after 'potentially unexplained illness'

Dr. Michael Osterholm said he'd be surprised if the illness was caused by the potential vaccine.

A promising COVID-19 vaccine trial has been paused after a patient involved in the study fell ill. Biopharmaceutical company AstraZeneca announced Tuesday that a "standard review" led to the discovery of a "potentially unexplained illness." 

"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 said

AstraZeneca's Phase III trial involves 30,000 people in the United States, including Minnesota recipients through a partnership with HealthPartners Institute. The patient whose possible side effect that triggered the pause is from the United Kingdom. 

The third phase of the vaccine trial launched in early September, with the 30,000 adult patients receiving the potential vaccine or a placebo. The goal of the trial is to assess efficacy and safety of the drug while monitoring systemic and immune reactions. 

"The trial did exactly what it's supposed to do. If we see a potential health issue in one of the recipients, then we have to go ahead and determine if that's associated with the vaccine or if it's just a chance occurrence," said Dr. Michael Osterholm, infectious disease expert at the University of Minnesota, in a Wednesday appearance on WCCO Radio

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Osterholm said the patient in the trial developed inflammation of the spinal cord, though Osterholm added that he "would be surprised if this is associated with the vaccine."

How long the trial will be paused is unclear. 

"We will be guided by this committee as to when the trials could restart, so that we can continue our work at the earliest opportunity to provide this vaccine broadly, equitably and at no profit during this pandemic," said Pascal Soriot, CEO of AstraZeneca. 

According to the Centers for Disease Control and Prevention, vaccine trials that pass Phase III can enter a fourth phase that features ongoing studies after the vaccine is approved and licensed. 

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