By Rocky Swift

TOKYO (Reuters – Takeda Pharmaceutical Co Ltd, Japan, stated Friday that it was human error that caused the metal contaminants to enter. Moderna (NASDAQ:) Inc COVID-19 vaccination doses were recalled.

Moderna, the Japan-based distributor of the vaccine, and Takeda stated in a recent report that while a Spanish producer discovered contamination in vials from July, the manufacturer was allowed to send supplies to Japan.

Japan’s authorities suspended three batches of Moderna shots that contained 1.63 Million doses, in August after they were notified. Moderna worked with Spanish manufacturer Rovi as well as Takeda to investigate the incident.

New research revealed that the problem was not due to incorrect assembly, but human error. It stemmed specifically from the misjudging of the 1mm space between the star wheel and stopper in the machinery that placed the vaccine vial tops.

The investigation involved five sequential lots, totaling 5, of Moderna COVID-19 vaccinations manufactured at Rovi in the period June 27-July 3. Three of the first three lots were shipped to Japan, but they were later recalled following discovery that particles inside 39 vials contained stainless steel.

After the July 2 discovery of particle contamination, a fourth lot did not pass inspection and Rovi also held onto a fifth lot. Moderna’s, Takeda’s and Japan’s health ministries were informed about the issues with Lots 4 and 5, but they were cleared for use as the “first three lots had passed inspection” and not considered to be affected.

According to an investigation, the wrong setup “led the issue to persist throughout the series five batches.”

The report stated that improved operating procedures, as well as the application of a precision tool, will prevent this issue from returning.

Both the companies and Japan’s health ministry said that stainless steel particles pose no health risks.