COVID-19 vaccine syringes ready for administration are seen in this photo. (Mainichi/Koichiro Tezuka)

       TOKYO -- An investigation of foreign substances discovered in Moderna Inc.'s COVID-19 vaccines that were scheduled to be used in Japan's southernmost prefecture of Okinawa found that they included debris generated when rubber stoppers on vaccine vials were scraped when filling syringes, the health ministry announced Aug. 29.

       The probe was conducted by Takeda Pharmaceutical Co., which is responsible for the domestic supply of the Moderna vaccine. The Ministry of Health, Labor and Welfare said there was no problem with the quality of the vaccine itself, and though the Okinawa Prefectural Government halted inoculations after finding the foreign substances, the ministry said "there is no need to withhold" vaccinations.

       According to the health ministry, foreign substances were found in a total of five vaccine-filled syringes on Aug. 27 and 28. Since the contaminated vaccines were not among the lots the health ministry had requested local bodies to halt the use of, Okinawa Prefecture suspended vaccination at inoculation sites that had the vaccine with the same lot number as the contaminated ones -- 3005293 -- from the evening of Aug. 28 to 29. No health hazards have been confirmed.

       The health ministry says the needle on the syringe needs to be pierced perpendicularly to the vial's rubber stopper, but it appears that part of the rubber stopper was scraped off and mixed into the vaccine as the needle was pierced at an angle. It had reportedly been confirmed that the vaccine in vials before needles were pierced into their rubber stoppers had been free of foreign substances.

       The health ministry also said debris from the rubber stoppers have on rare occasions got mixed into the vials in the manufacturing process, and revealed that about 20 such cases had been confirmed in 35 lots so far in Japan.

       Following the recent discovery of foreign substances that appeared to be small metallic particles in unused vaccine vials at eight inoculation sites in five prefectures including Tokyo, the health ministry halted the use of the contaminated lot 3004667 as well as lots 3004734 and 3004956, which had been manufactured around the same time.

       (Japanese original by Hidenori Yazawa, Lifestyle and Medical News Department)

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