On Tuesday, Japan’s health minister said researchers had found a possible cause for the Moderna vaccine’s contamination.
Norihisa Tamura explained that the foreign matter found in the shots manufactured by Moderna Inc., which led to authorities to suspend millions of Covid-19 vaccine doses in Okinawa, was likely caused by improperly inserting needles into the vials.
Moderna shots were temporarily halted in southern Okinawa prefecture after discovering that the vials and syringes were contaminated.
But the Health Ministry said later that needles might have been improperly stuck in the vials, breaking off pieces of rubber stoppers.
“Whatever the reason (for the foreign matter) we have heard that there is no safety or other issues,” Norihisa Tamura told reporters.
It is not uncommon for foreign material to enter a vial with other jabs, the health minister stated, adding that specialists would continue collecting information.
Japanese health officials had suspended more than 2.6 million Covid-19 shots on Sunday.
The move followed reports of two possible deaths related to vials contaminated with foreign substances.
Back then, the health minister announced that a further one million doses would be suspended after investigators found contaminated vaccine vials in Gunma prefecture near Tokyo and on Okinawa.
Reuters reported that a local official in Gunma had discovered a black substance in a Moderna vaccine vial.
In Okinawa, pink and black foreign substances were detected in vials and syringes, the news agency added.
On Monday, the Health Ministry said some affected vaccines could have been contaminated by pieces of the vial’s broken rubber stopper, adding that Moderna shots had been suspended as a precaution since no safety problems had yet been reported.
Moderna’s doses were shipped to 863 Japanese vaccination centers, and some shots from that batch were administered to approximately 500,000 people.
Japan has also launched an investigation into the cause of the two reported fatalities, but health experts believe it’s not related to the contaminants.
Moderna and Rovi, a Spanish company that bottles Moderna vaccines for Japan, said vaccines could have been contaminated by manufacturing problems on a Rovi’s production line.
Both the vaccine manufacturer and the Japanese Health Ministry launched investigations into the matter.
The three vaccine batches’ suspension comes as Japan tries to speed up inoculations.
Taro Kono, the minister in charge of the vaccination campaign, said the government expected to speed up vaccine shipments to municipalities affected by shortages.
The government wants to complete the first two doses for each person before starting to give booster shots, the minister added.
