This week, it was reported that AstraZeneca is voluntarily halting the late-stage trial for its coronavirus vaccine. The company chose to halt the trial after a woman in the UK who took the vaccine came down with transverse myelitis, which causes inflammation of the spinal cord.
According to the National Institute of Neurological Disorders and Stroke, the exact cause of transverse myelitis is often never known, but it is commonly linked to viral infections — and it can also be triggered by vaccines.
After the news that AstraZeneca is investigating the cause of the trial participant’s illness, analysts weighed in about the impact it could have. SVB Leerink’s Andrew Berens wrote in a client note that if the woman’s case is indeed linked to the coronavirus vaccine, AstraZeneca’s trial could be “terminated.” Another Leerink analyst, Geoffry Porges, also said that the trial halt is “the worst kind for vaccine developers — rare, severe, complex in presentation, difficult to diagnose, and plausibly associated with the vaccine technology."
He also estimated that it could take months to prove that the illness was not caused by the vaccine, which has “implications for the development strategy (but not the development risk) for all the other COVID vaccines in pivotal trials."
But not everyone sees the outlook as quite so grim. The Financial Times, quoting sources “familiar with the matter,” reported that AstraZeneca may be able to get the trial back up and running as early as next week. In a statement, the company said that it is “working to expedite the review of the single event to minimize any potential impact on the trial timeline.”
For now, it remains unclear how the trial halt will impact other vaccine candidates in development. Because AstraZeneca’s vaccine, which it is developing with University of Oxford, was made with an adenovirus platform, it is most likely going to impact other candidates — such as those from J&J and CanSino — developed with the same kind of technology.
The other two coronavirus vaccines in late-stage trials in the U.S. — from Pfizer/BioNTech and Moderna — were developed using mRNA technology.
But Leerink’s Dr. Mani Foroohar wrote in a research note this week that the AstraZeneca situation could rattle confidence in all of the candidates in development.
“To the extent that this episode leads to broader vaccine hesitance among the general population or greater regulatory scrutiny across mechanisms of action, all vaccine developers may have reason for concern," he wrote.
