There isn’t one. The New York Times reports:

Most countries contract with several makers, in part to avoid critical dependence on any one supplier. And though countries other than the United States had placed orders with Chiron for a smaller part of their vaccine needs, no other country was so dependent on the Liverpool factory.

In England, for example, the National Health Service bought the 14 million doses of flu vaccine that it needed from five or six suppliers, said Alison Langley, a spokeswoman for the Department of Health. Two million of those doses were to have come from the Chiron factory in Liverpool. “But we were able to make that up with additional purchases from elsewhere,” Ms. Langley said.