According to a Bloomberg article published Thursday morning, the European Medicines Agency (EMA) has begun a rolling review of AZD1222, the COVID-19 vaccine candidate being jointly developed by AstraZeneca (AZN 0.46%) and the University of Oxford.

A rolling review is one in which regulators analyze data from clinical trials that are still underway in order to determine whether they should approve a drug or vaccine. Such reviews are reserved for emergency situations; the coronavirus pandemic certainly qualifies. The EMA had previously stated it would conduct rolling reviews of promising vaccine candidates.

A syringe being filled with a vaccine from a vial.

Image source: Getty Images.

Remdesivir, a Gilead Sciences antiviral drug that was repurposed to treat COVID-19, won its EU approval for that use on a rolling review. The period of time from the start of that review to approval was three months.

Meanwhile, an article published on Wednesday, this one from Reuters, said that the U.S. Food and Drug Administration has widened its investigation into the case of a serious illness that developed in a patient who was participating in clinical testing of AZD1222 in the U.K.

The article, which cited "three sources familiar with the details," said that the FDA has made a request for data from the study. During the trial, the patient developed what appeared to be transverse myelitis, a spinal inflammation disorder. The data will apparently be conveyed to the regulator within days. Meanwhile, the U.S. arm of AZD1222's clinical trial has been suspended; the section of the study being conducted in the U.K. has resumed after a brief suspension.

AstraZeneca has not yet commented on either report.