Though the contamination is not currently known to be hazardous, Japan has paused distribution
Japan halted all uses of the country's Moderna COVID-19 vaccines on Thursday as a precaution following several reports of vial contamination.
Japan’s pause on its 1.63 million doses prompted a wave of canceled vaccinations as Moderna promised to address the issue.
Currently, both Moderna and Japan assess that the contamination does not affect a dose’s safety or effectiveness, but stopped distribution as a safeguard in the interim.
"Moderna confirms having been notified of cases of particulate matter being seen in drug product vials of its COVID-19 vaccine," the company responded in Reuters. Moderna expressed that the matter in the vial could potentially be attributed to a manufacturing mishap along its production line, which is based in Spain, under the pharmaceutical company Rovi.
Rovi, which bottles the Moderna vaccines, released reassurances that it is investigating the incident. The company stated that the contaminated vials are localized to a few batches which were bound for Japan.
Evidence of contamination was initially uncovered by Takeda Pharmaceutical, Moderna’s partner in vaccine distribution, on August 16.
Following an investigation into which vials were affected, the tainted batch (as well as two adjacent batches) were placed on hold.
According to the Japanese Defense Ministry, the contaminated vaccines, which amount to 565,400 doses, were distributed in the country’s western prefecture.