OTTAWA -- It could be weeks before Health Canada is able to say for sure whether the first delivery of 300,000 Johnson & Johnson COVID-19 vaccine doses can be used due to the ongoing quality control review, according to the agency’s chief medical adviser.

“We're still getting more information. Just this past week we had additional information from Johnson & Johnson about the quality of those lots, we've got our scientists reviewing that. So we will have more information in the next couple of weeks on that, but it really depends on looking at that data,” said Dr. Supriya Sharma in an interview on CTV’s Question Period.

On April 30, Health Canada announced it would be holding back the doses that had just landed for further review after learning that a drug substance used in the vaccine was produced at the Emergent BioSolutions' Baltimore facility, which had an error last month that led to millions of J&J doses being ruined. 

“The drug substance is the active ingredient that undergoes further processing before becoming the final product," the agency said at the time.

Health Canada noted that the final Janssen vaccines were manufactured at a different site located outside of the U.S., however, the agency said at the time it needed to ensure the doses met quality standards before they are administered to Canadians.

“We will only release those lots if we can assure the quality of those products and then it matches what we actually saw when we authorized the vaccine,” Sharma said. Canada authorized Johnson & Johnson’s single-shot COVID-19 vaccine on March 5, and the federal government has ordered 10 million doses, though none have been administered here yet.

Sharma said that Health Canada continues to work with Janssen and the U.S. Federal Drug Administration (FDA), who went into the plant and conducted inspections.

The FDA had stopped AstraZeneca from using the Baltimore facility earlier this month and halted production of J&J’s vaccine at the plant as it began investigations into "multiple areas of concern," including a vaccine ingredient that did not meet quality standards.

With files from’s Brooklyn Neustaeter