(CNN) -- Drugmaker Johnson & Johnson says it had a glitch in a plant that's helping make its COVID-19 vaccine.
J&J is producing the only vaccine authorized in the U.S. that requires only one shot.
The company says it found a quality issue in one batch of a vaccine ingredient made at a plant in Baltimore. The batch was part of a test run.
The Emergent plant - which is a contractor - is yet to be authorized to make the ingredient in question.
The statement came after J&J announced it would meet its goal of delivering 20 million vaccine doses in March. The company says it's still on track to deliver 24 million more doses next month.
The New York Times reported the quality problem ruined as many as 15 million potential vaccines.