The U.S. government will set aside about $1 billion in existing funds for developing a vaccine for the H1N1 flu, a virus from swine origin, according to Health and Human Services Secretary Kathleen Sebelius.

The funds will be used for clinical studies will take place over the summer and for commercial-scale production of two potential vaccine ingredients, according to a released statement.

New orders will be made for companies that have existing contracts and hold U.S. licenses for flu vaccines

Companies allowed to sell flu shots in the U.S. include Sanofi Aventis SA, Novartis AG, GlaxoSmithKline PLC and CSL Ltd, according to Reuters. AstraZeneca’s MedImmune sells a nasal spray flu vaccine.