Japan on Tuesday reported a new suspected contamination case involving a vial of Moderna’s coronavirus vaccine.
According to Reuters, black particles were found in one vial while officials were analyzing the vaccine supply for foreign substances before it was sent out for use.
The particles were identified as bits of rubber stopper material used in the manufacturing process, Reuters noted.
Medical staff in the country have been advised to visually inspect all vaccine vials for discoloration or foreign materials before use, the wire service added.
The incident is the fourth Japan’s vaccine campaign has seen in less than a week.
Last week, Japan put a pause on nearly 1.63 million doses of the Moderna vaccine after the supply was reportedly contaminated. Though Moderna said at the time that no safety issues were found, the company and its bottling partner, Spanish pharmaceutical company Rovi, acknowledged that there could be an issue with manufacturing.
Moderna’s distributor in Japan, Takeda Pharmaceutical Co. Ltd., reportedly collected that vial though more than 3,700 people had already received shots from the same lot.
European safety regulators have launched an investigation, Reuters reported.
All of the incidents occurred as Japan battles a surge of coronavirus infections driven by the highly contagious delta variant.
Japan has reported about 1.5 million coronavirus cases and 16,080 deaths since the start of the pandemic, according to Johns Hopkins University.
Nearly 131 million vaccine doses have been distributed in the country, with nearly 59 million people fully vaccinated against COVID-19, Johns Hopkins reported.