Pharmaceutical company Moderna said consignments of defective COVID-19 vaccine shipped to Japan were contaminated with stainless steel particles, but the company does not expect this to pose an “undue risk to patient safety.”
The Japanese government has decided to block more than 1.6 million doses of Moderna vaccine due to fears of contamination. Moderna confirmed on Wednesday that "steel particles" were found in some of the vaccine vials.
Japanese authorities are also investigating the deaths of two people who were vaccinated with one of the three batches before they were withdrawn.
In a joint statement with its Japanese partner, Takeda, Moderna says one of the three suspended batches was contaminated by defects in a production line at a plant operated by Spanish contractor ROVI Pharma Industrial Services.
Takeda and Moderna said there was "no evidence" at this stage that the deaths could have been caused by vaccines, but stressed the importance of an official investigation into the matter.
“The rare presence of stainless steel particles in Moderna COVID-19 vaccine does not pose an undue risk to patient safety and does not adversely affect the product's benefit /risk profile,” the companies said in a statement.
Metal particles of this size injected into a muscle can cause a local reaction, but are unlikely to go beyond this, pharmacists insist.
“Stainless steel is commonly used in heart valves, joint replacement, metal sutures and braces. Thus, it is not expected that the introduction of particles identified in these batches in Japan will lead to an increased medical risk, ”it said.
Moderna shares are up more than 2% after this announcement.