Japan has temporarily suspended the use of an additional one million doses of American Moderna coronavirus vaccine, after foreign substances were spotted in some of the batches.
The Okinawa prefecture, in southern Japan, as well as Gunma prefecture near the capital Tokyo, postponed their vaccination program on Sunday after receiving reports of contaminants in some vials.
An unnamed official from Gunma prefecture told Reuters a tiny black substance was found in a Moderna vaccine vial, while in Okinawa, black substances were spotted in syringes and a vial, and pink material was also found in a different syringe.
Following the latest reports of vaccine contamination, the Japanese Health Ministry said on Monday that some of the incidents may have been due to needles being incorrectly inserted into vials, breaking off bits of the rubber stopper, adding that other vials from the lots can continue to be used.
This comes as Japan is investigating the death of two men who received shots from tainted Moderna batches -- though the cause of their death is unknown.
The government reported the deaths on Saturday, saying no safety or efficacy issues had been identified and that the suspension is a precaution.
Takahiro Kinoshita, a physician and vice chair of Cov-Navi, a vaccine information group, said, "It is unlikely, in my opinion, that contamination of foreign substances led directly to sudden deaths."
"If the contaminated substances were dangerous enough to cause death for some people, probably many more people would have suffered from some symptoms after the vaccination. However, further investigations are definitely needed to evaluate the harm of the particular doses in question."
The new development came after Japan halted the import of 1.6 million doses of Moderna’s COVID-19 vaccines when the domestic distributor received reports of contaminants in some vials.
The Japanese health authorities made the announcement on Thursday after contaminants were discovered in some 40 doses of the vaccine at eight different locations across the country.
Taro Kono, the minister in charge of the vaccination program, said some 500,000 people have received shots from those supplies.
Spanish pharma company Rovi, which bottles Moderna vaccines for markets other than the United States, said the contamination could be due to a manufacturing issue on a production line.
Takeda Pharmaceutical, the company that distributes the Moderna shot in Japan, said on Monday that investigation is ongoing.
Meanwhile, the official in Gunma said the lots affected by the contamination spotted in the prefecture as well as in Okinawa are different from the 1.6 doses suspended after the two deaths.
The official went on to say that these vaccines have been administered to 4,575 people in Gunma, but the prefecture has heard no reports of ill health.
The suspension of Moderna supplies, affecting more than 2.6 million doses in total, comes as Japan is battling a record surge of virus cases driven by the more contagious Delta variant, raising concerns that medical systems in some parts of the country could be overwhelmed. New daily infections exceeded 25,000 this month for the first time amid a slow vaccine rollout.
After getting off to a slow start, Japan is now administering over a million vaccine doses each day. Currently, about 43 percent of the population is fully vaccinated.
New daily infections exceeded 25,000 this month for the first time amid a slow vaccine rollout.
Nicholas Rennick, an Australian doctor practicing at the NTT Medical Center in Tokyo, described the contamination “a serious problem,” but stressed that given rising COVID-19 cases, Moderna vaccinations should "continue with appropriate precautions."
Japan is looking into the possibility of mixing shots of AstraZeneca's vaccine with those developed by other drugmakers to speed up vaccination.