GlaxoSmithKline ($GSK) is recalling 1.7 million doses of its quadrivalent flu vaccine that was manufactured at a plant that ran into a series of manufacturing issues last year including an FDA warning letter. The company says there are questions about whether the vaccine is retaining its potency.
"As part of stability testing, GSK observed loss of potency below the minimum specification prior to product expiry for the B strains included in the vaccine," the drugmaker said in a letter to distributors and healthcare providers issued last week. "The lots are being recalled due to the potential for reduced efficacy offered by the vaccine and not as a result of any identified safety concern."
In an emailed statement, GSK spokeswoman Anna Padula said the voluntary recall to U.S. customers was "for all remaining doses of FluLaval Quadrivalent Thimerosal-Free (Influenza) Vaccine, in the Pre-Filled Syringe, which were provided to the U.S. market for the 2014/15 flu season." According to the Associated Press, it was unknown how many of the 1.7 million units were still on the market since 99% of it was distributed in 2014, before the potency began to wane.
In a follow-up telephone interview, Padula said the problem that led to the recall was not tied to the issues raised last year by the FDA in the warning letter to the plant in Quebec City where the vaccine is manufactured. She said the Canadian plant does all of the manufacturing of the vaccine except the fill and finish work, which is done at a plant in Belgium. She said it was "premature to comment on the potential root causes," and whether they were tied to the manufacturing or the fill/finish work, "because we are still investigating."
The company had to actually reduce the amount of vaccine it shipped last year after a series of manufacturing problems at the Quebec City plant. The FDA issued a warning letter in June in which it raised concerns about bacterial contamination, questioning the quality of the new FluLaval vaccine and its intermediates. The agency pointed out that there have been problems with the purified water at the plant for years, including alerts because of organisms, including Ralstonia pickettii and Achromobacter xylosoxidans, both of which have been implicated in product contamination that dates back to 2011.
GSK's efforts to fix some of the issues did not resolve them, leading GSK to resort to a manufacturing process it had used in the past. But then it had to temporarily suspend production to investigate "irregular results" in quality-control monitoring. It also reported getting an "invalid test result on one component of the trivalent vaccine," which required retesting. The issues led it to reduce the amount of vaccine that it could ship from the plant.
This past season's flu vaccines posted one of the worst efficacy rates in recent memory. That had been blamed on the fact that the viral strains the vaccines contained did not closely match the ones that ended up circulating.