PARIS (Kyodo) -- A lot of Moderna's COVID-19 vaccine doses in which contaminants were detected had only been shipped to Japan, the Spanish manufacturer for the U.S. biotechnology company said Thursday.
"The detection of this particulate matter refers to certain vials of one product lot distributed exclusively in Japan," the Spanish pharma company Rovi said in a statement, adding it is conducting an investigation into the matter and cooperating with health authorities.
As a precaution, Japan suspended Thursday the use of around 1.63 million doses of Moderna vaccine after contaminants were found in some unused vials.
Both Moderna and Japanese drugmaker Takeda Pharmaceutical, which is in charge of the sale and distribution of the vaccine in Japan, said they had not received any reports regarding safety issues.
"The origin of this manufacturing incident may be in one of Rovi's manufacturing lines," said the company. "As a precaution, this lot and two adjacent lots have been put on hold."
Under a contract with Moderna, a Rovi factory in the suburbs of Madrid handles the final process of vaccine production for doses shipped outside the United States, filling the bottles with raw materials produced by a Swiss company.