Moderna Inc has withheld supply of about 1.63 million doses in Japan after it was notified of contamination of its Covid-19 vaccine vials with particulate matter, the US vaccine maker said on Wednesday.

The contamination, the company said, could be due to a manufacturing issue in one of the production lines at its contract manufacturing site in Spain.

The lot with complaints had 565,400 doses and "out of an abundance of caution" Moderna has put on hold the lot and...