"AstraZeneca ... is already working to understand the existing cases, epidemiology and possible mechanisms that explain these extremely rare cases," RIA Novosti reported.
The company also added that it is actively working with regulators to amend the description of its coronavirus drug.
Earlier, the European Medicines Agency announced the need to include cases of blood clots on the list of rare side effects of the Vaxzevria vaccine (formerly known as AstraZeneca).