Japan has suspended the use of approximately 1.63 million doses of the Moderna vaccine due to contamination, BBC News reports.
Japan's health ministry stated that "foreign materials" were found in a number of doses from a batch of roughly 560,000 vials.
Takeda Pharmaceutical, which sells and distributes the vaccine in Japan, said Moderna put three batches on hold "out of an abundance of caution". The company said an issue at a manufacturing site in Spain was likely the cause, but did not elaborate further.
Moderna said that it would work with vaccine regulators and Takeda to investigate the matter further, stating that "to date, no safety or efficacy issues have been identified." There are no details of what the "foreign objects" are, but Takeda described it as particulate matter.
Reports of contamination also came from seven other vaccination centres, according to the Japan Times newspaper, with 390 doses found to have been contaminated.
Japan's health ministry has published the batch numbers so that people who received their shot before the suspension can check to see if they got a potentially contaminated dose.