A company with an early contract to produce coronavirus vaccine hid evidence of problems.

Emergent BioSolutions, a longtime government contractor hired to produce hundreds of millions of coronavirus vaccine doses, hid evidence of quality control problems from Food and Drug Administration inspectors in February 2021 — six weeks before it alerted federal officials that 15 million doses had been contaminated.

The disclosure came in a new report by the Democratic-led House Committee on Oversight and Reform. The report, based on internal company emails, documents and interviews, sheds new light on Emergent executives’ own worries about deficiencies in the company’s quality control systems at its troubled Bayview plant in Baltimore.

The report, released Tuesday morning by the House and the Select Subcommittee on the Coronavirus Crisis, said that all told, nearly 400 million doses of coronavirus vaccine manufactured by Emergent had to be destroyed “due to poor quality control,” including about 240 million doses in late 2020 and early 2021. Previous estimates of lost vaccine were far lower; no contaminated doses were ever released to the public.