The Centers for Disease Control and Prevention immediately has begun tracking new sources to supplement the unexpected flu vaccine shortage, director Julie Gerberding announced Wednesday. The expected U.S. supply of the vaccine was cut nearly in half Tuesday when British authorities suspended the license of second-leading world supplier Chiron.

Aventis Pasteur, the provider of 55 million of this year’s doses for the U.S., said because of overproduction, it could supply the U.S. with an additional one million doses, bringing its total to 56 million, Gerberding said.

Meanwhile, officials are contacting other manufacturers for extra doses, while doctors and other U.S. vaccine providers are being asked to follow a voluntary redistribution system to give priority to individuals in the high-risk category of contracting the flu. Nursing home residents, healthcare providers and the elderly fall into this category.

The government should have had better plans to offset the problems caused by a vaccine shortage, Gerberding and legislators say. Gerberding has called on the federal government to overhaul its current system for supplying and distributing vaccines. A shortage of this magnitude has been a long time coming, the New York Times reported Thursday. Five companies providing the amount of vaccines that 25 companies used to supply is cited as one of the reasons for the shortage prediction.