GlaxoSmithKline P.L.C. said Friday that the Food and Drug Administration wanted more information about the company's experimental vaccine MenHibrix before deciding whether to approve the immunization.
The combination vaccine is designed to prevent two types of meningitis in infants and toddlers: meningococcal disease and Haemophilus influenzae type b, the London-based drugmaker said Friday in an e-mailed statement.
The company has major operations in the Philadelphia area.
Glaxo said it received a complete response letter about the booster shot from the FDA, which the agency sends when it has completed a review of an application's file but needs some more questions answered, the Wall Street Journal reported online Friday.
Glaxo "will work to respond to the questions posed by FDA" and "remains committed to making this vaccine available in the United States," the company said.
Shares of Glaxo closed up 69 cents, or 2 percent, at $34.97 in regular trading. Shares were lower in after-hours trading.