The Food and Drug Administration has issued a warning letter to drug maker Sanofi Pasteur Inc. over concerns about problems at a Pennsylvania manufacturing plant, the agency said Monday.
Sanofi Pasteur had reported that some batches of its influenza vaccine had failed sterility tests, prompting an FDA inspection of the plant in Swiftwater, Pa., in April.
But the agency said it issued the warning letter because the source of the contamination had not been determined, meaning that the agency could not be sure the problem had been corrected.
The letter is an advisory action and the plant can continue making vaccine, said Dr. Karen Midthun, deputy director of the FDA's Center for Biologics Evaluation and Research.
Sanofi Pasteur, a unit of Paris-based Sanofi-Aventis, said in a statement that it was working closely with the FDA and that many of the agency's concerns "have either been resolved or the FDA has accepted our proposed remediation plans."
The company added: "We are confident that we will meet our manufacturing goal of approximately 50 million doses of influenza vaccine for the U.S. market."