The Spanish pharmaceutical company Laboratorios Farmaceuticos Rovi, which produces the COVID-19 vaccine from the American firm Moderna, said it is investigating an incident involving unknown impurities in drugs found in Japan, Reuters reported.

ROVI noted that impurities are only present in some vaccine lots destined for Japan. A company spokesman also said that the company has not suspended production of the drug, and the timing of the investigation remains unknown.

The Japanese health ministry announced the suspension of the use of about 1.63 million doses of Moderna vaccine, and also began an audit in connection with the incident.