Moderna Inc. and Takeda Pharmaceutical Co. Ltd said they are working with the Japanese government to recall three batches of COVID-19 vaccine after an investigation confirmed stainless steel contaminants in some vials, local media reported Thursday.
The health ministry said Wednesday the foreign substances found in some vials of Moderna Inc.'s vaccine distributed in Japan were confirmed to be stainless steel, which seemed probably mixed during the manufacturing process.
The most possible reason for contamination was related to friction between two pieces of metal in the machinery that puts stoppers on the vials, Moderna said in the joint statement with Takeda, which distributes the Moderna vaccine in Japan.
Moderna performed the investigation in partnership with Takeda and Spanish manufacturer Rovi, which operates the plant where the contamination occurred.
Japan's health ministry said it did not believe the particles of stainless steel caused any additional health risk based on information from the companies' investigation.
"Stainless steel is routinely used in heart valves, joint replacements and metal sutures and staples. As such, it is not expected that injection of the particles identified in these lots in Japan would result in increased medical risk," Takeda and Moderna said in a joint statement.
Administration of Moderna shots totaling 1.63 million doses was suspended in Japan last week after 39 vials were found to contain foreign material. All the vials came from a single lot, but shots from two other lots produced in the same Rovi manufacturing line were halted as a precaution.
The use of other Moderna vaccine doses from different batches was also temporarily suspended in three areas in Japan this week. In some cases, the foreign substances have been found in unused vials, whereas others appear to be caused when bits of the vials' rubber stopper breaks off when needles are incorrectly inserted.
The contamination issue attracted more attention after the health ministry said Saturday that two men, aged 38 and 30, died in August within days after getting their second Moderna doses. Each had received a dose from one of the suspended lots.
The cause of death in the two cases is still under investigation. Takeda said there showed no evidence the fatalities were triggered by the vaccine.
"The relationship is currently considered to be coincidental," the company said in the statement.
