Contaminant in Moderna vaccines suspected to be metallic particles: NHK

A contaminant found in a batch of Moderna Inc's COVID-19 vaccines delivered to Japan is believed to be a metallic particle, Japanese public broadcaster NHK reported, citing sources at the health ministry.

Japan on Thursday suspended the use of 1.63 million doses shipped to 863 vaccination centres nationwide, more than a week after the domestic distributor, Takeda Pharmaceutical, received reports of contaminants in some vials.

The NHK report, published late on Thursday, cited ministry sources as saying the particle reacted to magnets and was therefore suspected to be a metal. Moderna has described it as "particulate matter" that did not pose a safety or efficacy issue.

An official at the health ministry said the identity of the contaminant has not been confirmed.

News of the contaminant could provide a fresh setback for Japan's inoculation drive as it struggles to persuade many - particularly among the youth - to get vaccinated.

On Friday, eight more prefectures entered a state of emergency bringing a total of about 80 percent of Japan's population under COVID-19-related restrictions. The government reported nearly 25,000 new infections and severe cases at a record 2,000 for Thursday.

The ministry has said the suspension of the Moderna batches was a precaution, but the move prompted several Japanese companies to cancel worker vaccinations and the European drugs regulator to launch an investigation.

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 in a production line and that it was conducting an investigation.

Moderna put the lot in question and two adjacent ones on hold.

A separate health ministry official said it would take "some time" to confirm how many shots from the contaminated batch had already been administered in Japan. Kyodo News reported that at least 176,000 shots have been used based on its own tally of figures reported by local municipalities.

So far, about 54 percent of Japan's population has received at least one dose, according to a Reuters tracker.