Lilly must also retain an independent third party to vet quality-testing data and other records as the treatment is manufactured at the facility in Branchburg, New Jersey, according to a letter on Monday from the Food and Drug Administration granting an emergency authorization for the drug’s use in treating COVID-19.

If a review discovers any issues, Lilly would be required to hold off on releasing any batches that haven’t already gone out to the public, the FDA said. The therapy, bamlanivimab, is authorized for use against mild-to-moderate Covid-19 in adults, including those who are 65 and older, and pediatric patients.

The potential that supply of the antibody therapies could be kept off the market could add to questions about how plentiful such drugs will be as the pandemic continues to worsen. In the U.S., infections are soaring again, with more than 142,000 new cases reported on Monday. The U.S. government is expected to allocate Lilly’s drug based on state-by-state infection data.

Spokesmen for Lilly didn’t immediately respond to requests for comment

The conditions follow the discovery by FDA inspectors of continuing problems at the plant in Branchburg, which is one of the sites the company is using to produce the antibody therapy. In an Oct. 2 memo, agency compliance officers wrote that findings from an inspection in July and August “support a major failure of quality assurance.”

The compliance officers recommended that the company receive a warning letter, one of the agency’s strongest enforcement measures, according to documents reviewed by Bloomberg News. Agency inspectors found that in some cases Lilly employees didn’t investigate potential quality problems and routinely overrode testing systems, according to the documents.

Lilly said last month after the July and August inspections were reported that it was working with the FDA on remediation efforts, and it was confident the issues didn’t affect drug quality or patient safety.

Lilly makes active ingredients for the Covid-19 drug, bamlanivimab, as well as for cancer drugs and a migraine medicine at the Branchburg, New Jersey, facility.

Any discrepancies in testing must be reported to the FDA every two weeks. Lilly also has to report any signals of potential contamination that arise, and inform the agency whether a recall is necessary, according to the FDA letter Monday.

The FDA also will require Lilly to recall any bamlanivimab the agency requests, a move the FDA doesn’t typically have strong powers to force in other circumstances.

Bamlanivimab relies on lab-made proteins that mimic the immune system’s ability to fight off the virus. Lilly has a manufacturing agreement with Amgen Inc. to help boost supplies.