AUGUSTA – The state on Wednesday asked health care providers to limit their supplies of flu vaccine to people who are most at risk of flu-related health complications.

The announcement came a day after British regulators unexpectedly shut down a major flu-shot supplier, citing problems at a factory in England that manufactured roughly 46 million doses destined for the United States.

The loss of the flu vaccine from Chiron Corp. poses a challenge to Maine’s vaccine supply during the upcoming flu season, health officials said.

“Our immediate focus will be on making sure that the vaccine supply we have reaches those who are most vulnerable,” Dr. Dora Anne Mills, director of the Maine Bureau of Health, said in a statement.

On Wednesday, the bureau asked health care providers to voluntarily restrict use of available vaccine to highest risk groups: babies, the elderly, pregnant women and people with compromised immune systems.

The announcement follows a similar warning from federal officials, who also on Wednesday urged healthy people to defer from getting flu shots.

This year Maine had ordered approximately 150,000 doses of flu vaccine for high-risk Mainers. About 123,000 of these doses were from Chiron, and nearly 28,000 doses were from Aventis.

Many private providers also purchase vaccine in addition to the state supply.

The Bureau of Health is assessing the amount of flu vaccine available in Maine through a survey of health care providers.

Flu vaccine is made using chicken eggs and takes months to make, meaning manufacturers cannot produce additional doses overnight.

Because no Chiron vaccine had been released to the general public, there will be no need for a vaccine recall.