Baltimore, Maryland - Johnson & Johnson said Wednesday that it found one batch of drug substance that did not meet quality standards at Emergent Biosolutions, a site not yet authorized to manufacture the substance for its single-shot Covid-19 vaccine.

The batch was never advanced to the filling and finishing stages of its manufacturing process.

Johnson & Johnson's comments follow a report on Wednesday by The New York Times saying that about 15 million doses of the company's vaccine had been accidentally ruined by human error after workers in the facility mixed ingredients incorrectly, with shipments of the vaccine delayed as a result.

The plant is run by Emergent BioSolutions, a manufacturing partner to both Johnson & Johnson and AstraZeneca, whose vaccine has yet to be authorized for use in the United States.

Johnson & Johnson stated that it continues to work with the Food & Drug Administration and Emergent toward the Emergency Use Authorization of the Emergent Bayview Facility.

The company is providing additional experts in manufacturing, technical operations and quality to be on-site at Emergent to supervise, direct and support all manufacturing of the Covid-19 vaccine.

Meanwhile, Johnson & Johnson said it was still on track to deliver more than 20 million vaccine doses it promised the US by Wednesday, as well as another 24 million doses by the end of April.

It is part of the company's plan to deliver 100 million single-shot vaccines to the US during the first half of 2021, aiming to deliver those doses by the end of May. The company continues to expect to deliver its Covid-19 vaccine at a rate of more than one billion doses by the end of 2021.