GlaxoSmithKline said it has received Food and Drug Administration approval to start shipping the 2013-2014 influenza virus vaccine to Centers for Disease Control and Prevention distribution centers and healthcare providers.

The Fluarix® Quadrivalent is the first intramuscular quadrivalent flu vaccine approved by the FDA for children under three, and has virus subtypes A and B within the shot. Most flu vaccines have three-strains, but the GSK product hits both B strains, the company noted.

The CDC placed an order for four million doses of Fluarix Quadrivalent. The company estimates it will provide 10 million doses of quadrivalent flu vaccines in the U.S. and between 22 to 24 million doses of flu vaccines overall during the flu season.