The pharmacist is accused of intentionally removing them from refrigeration so they would spoil.

Some of the doses in question were administered before hospital officials determined the medication made by Madonna had been left unrefrigerated long enough to render them ineffective.

The remaining doses were discarded.

The pharmacist, who has not been publicly identified, worked at Aurora Medical Center in the Milwaukee suburb of Grafton.

Aurora Health Care Medical Group President Dr Jeff Barr said Madonna has assured the hospital that those doses removed from refrigeration posed no safety issue to those who had received an injection.

Importantly, there is no evidence that the individual in question tampered with the vaccine in any way other than removing it from refrigeration, leading to what is known as denaturing the vaccine.

When the misplaced vials were found on December 26th, the pharmacist said it was an inadvertent error.

But hospital officials said he admitted on Wednesday to intentionally removing the vaccine from cold storage.