By AI HEPING in New York | China Daily Global | Updated: 2021-04-02 13:51 Share CLOSE A nurse draws from a vial of Johnson & Johnson COVID-19 vaccine, in Los Angeles, California, US, March 25, 2021. [Photo/Agencies] Johnson & Johnson said it is sending additional experts to oversee production of its COVID-19 vaccine at a plant in Maryland where human error ruined millions of its one-dose vaccines. The plant is owned by a company that reportedly has been cited by US health officials for quality-control problems. Emergent, a contract manufacturer based in Gaithersburg, Maryland, has been making the main ingredient for the pharmaceutical company's vaccine at one of its plants in Baltimore known as Bayview.