LONDON (AP) — The pharma giant AstraZeneca has requested that the European authorization for its COVID-19 vaccine be pulled, according to the EU medicines regulator.

In an update on the European Medicines Agency’s website Wednesday, the regulator said that the approval for AstraZeneca’s Vaxzevria had been withdrawn “at the request of the marketing authorization holder.”

AstraZeneca’s COVID-19 vaccine was first given the nod by the EMA in January 2021. Within weeks, however, concerns grew about the vaccine’s safety, when dozens of countries suspended the vaccine’s use after unusual but rare blood clots were detected in a small number of immunized people. The EU regulator concluded AstraZeneca’s shot didn’t raise the overall risk of clots, but doubts remained.

Partial results from its first major trial — which Britain used to authorize the vaccine — were clouded by a manufacturing mistake that researchers didn’t immediately acknowledge. Insufficient data about how well the vaccine protected older people led some countries to initially restrict its use to younger populations before reversing course.