The European Union’s medicine regulator released documents Wednesday that showed a possible, rare side effect of AstraZeneca’s COVID-19 vaccine.
Safety updates from the European Medicines Agency showed that the rare nerve disorder known as Guillain-Barré syndrome has been added as a possible side effect of AstraZeneca’s COVID-19 vaccine, according to Reuters.
The EMA said that a relationship between Guillain-Barré syndrome and the company’s Vaxzevria caused 833 syndrome cases from the reported 593 million doses administered by July 31.
The European watchdog further categorized the potential side effect as “very rare,” according to the wire service. The label represents the lowest-frequency category for the side effect.
Guillain-Barré syndrome is a rare, auto-immune disorder in which the body attacks itself and damages its nerves.
The AstraZeneca vaccine has not been approved for emergency use in the United States.
In March, the use of the company’s product was put on pause in several European countries after reports that the shot could be associated with rare blood clots in patients who received the jab.
However, the use of the shot resumed in Europe the same month.
The U.S. Food and Drug Administration has also warned that Guillain-Barré syndrome is a very rare, but possible, side effect in Johnson & Johnson vaccines, according to Reuters.