"Currently, no link has been confirmed between these deaths and the Moderna vaccine, but we believe it is important to carry out a formal probe to investigate the matter further," Takeda said in a statement. Japanese use of some of the 1.63 million vaccine doses produced by CDMO Rovi in Grenada, Spain, had been suspended late last week due to fears of a contamination risk. Some of the doses had already been deployed for shots.

The ministry previously said that some of the doses from three identified lot numbers distributed to 863 vaccination sites across the country contained particulate matter. Each of the two people who died – described as men in their 30s with no underlying health conditions – had received a Moderna dose from one of three suspended lots.

Rovi said on its website that the possible contamination could have resulted from a “manufacturing incident” in one of its production lines producing exclusively for Japan. Local media, quoting the health ministry, said the particulate matter had been identified as metallic. 

Over the weekend, Japanese media also reported that a vaccination center on the island of Okinawa had also discovered doses of Moderna vaccine containing foreign material, but that these were not part of the suspended lots.

Moderna said it is “proactively communicating” with Japan's health authorities as the investigation proceeds and remains committed to working “transparently and expeditiously” with its partners and regulators to address any potential concerns.

Alongside Takeda, Rovi and Moderna, the health ministry will conduct its own investigation into the deaths to establish whether the vaccine may have played a role.  Takeda said results from laboratory tests will be available in the coming days.

Author: Dede Williams, Freelance Journalist