Japan has put on hold a batch of Moderna’s COVID-19 vaccine after a pharmacist saw several black particles in one vial of the vaccine. The pharmacist saw some foreign substance in one vial of the vaccine in Kanagawa Prefecture while checking it before use, according to authorities.

Some 3,790 people had already received shots from the batch. The rest of the batch has now been put on hold, reports the BBC. Earlier, Japan suspended the use of about 1.63 million Moderna doses due to contamination.