Moderna said today that contaminated batches of its coronavirus vaccine shipped to Japan contain stainless steel particles and that it does not expect this to pose “an undue risk to patient safety.”
The American laboratory is facing major setbacks in Japan, which suspended more than 1.6 million doses of the Moderna vaccine after detecting foreign substances.
Authorities are also investigating the deaths of two men who received doses from a contaminated batch, although the cause of death is currently unknown.
In a joint statement with its Japanese partner Takeda, Moderna said contamination in one of the three suspended batches refers to production line failures at a factory run by its Spanish contractor, ROVI Pharma Industrial Services.
“The rare presence of stainless steel particles in the Modern Covid-19 vaccine does not pose an undue risk to patient safety and does not negatively affect the risk/benefit profile of the product,” the statement said.
Metal particles injected into a muscle can cause a localized reaction, but are unlikely to cause anything else, he added.
“Stainless steel is commonly used in heart valves, joint prostheses, sutures and metal staples. As such, injection of the particles identified in these lots in Japan should not result in an increased medical risk,” he said.
Moderna added that, at the moment, there is no evidence that the two deaths were related to the vaccine and “currently it is considered a coincidence”. An investigation is ongoing.
About 46 percent of Japan’s population was fully immunized against the coronavirus, at a time when the country is experiencing a record increase in infections with the more contagious delta variant.
The pandemic has killed around 16,000 in Japan, which enforces harsh restrictions in large parts of the country.