DES MOINES - Iowa health officials scrambled Tuesday to react to a potential worldwide shortage of flu vaccine stemming from problems at a British vaccine manufacturer.

The Iowa Department of Public Health said priority for inoculation should go to people at highest risk of complications from the illness, such as children aged 6 to 23 months, people over 65, pregnant women and child-care workers.

"We are asking the general public for their cooperation. If you are not in a high-risk group, please do not get a flu vaccine at this time," said Mary Mincer Hansen, the department's director, at an afternoon news conference.

The vaccine maker, Chiron Corp., had its license yanked by the British government because of quality-control concerns at a Liverpool production plant. Hansen had no other details about the reason for the penalty.

Chiron was expected to provide roughly half of all doses in the nation. About 54 million vaccines, produced by Aventis, will be used this year. In Iowa, each medical group does its own ordering, so it's difficult to know the total number of doses ordered or Chiron's share of those doses.

"This is the first time in my memory that we will enter the season with a vaccine shortage," said Tom O'Rourke, director of the Black Hawk County Health Department.

Dr. Patricia Quinlisk, the state epidemiologist, put the anticipated shortage in personal terms.

"I've gotten a vaccine every year since 1975. I will not be getting the vaccine this year because I am at low risk," she said at the news conference.

Tuesday morning, county health departments and hospitals across Iowa rushed to assess their vaccine supplies and prepare answers to the anticipated flood of patient questions.

In Waterloo, the Visiting Nurses Association said they ordered more than half of this year's vaccine supply from Chiron. They are awaiting further instructions from IDPH before proceeding with most vaccines.

"This was kind of a surprise for us," said Debbie Crawford, the association's executive director. "You just never know with the flu vaccine. We thought it was late enough that we would be OK, but here we are, two days into the season and now we just have to deal with it."

The threat of a shortage this year follows a 2003-04 flu season in which Iowa was hit hard by the illness and an emergency supply of the vaccine had to be released by state officials.

Last December, Iowa was one of 24 states listed by the national Centers for Disease Control and Prevention as having a widespread flu outbreak. Flu cases were reported in all 99 counties and school districts covering 19 counties reported at least 10 percent of students absent because of the illness.

State officials predict this year's season will be moderate.

Most hospitals recommend patients get flu shots in October through December, preceding cold-weather months when the illness is usually at its worst.

Courier Staff Writer Emily Christensen contributed this article.

Dan Gearino can be reached at (515) 243-0138.