Woodstock resident Myra Vicchio was on a mission this week when she went to the Giant supermarket in Ellicott City. She wanted a flu shot, and her medical center had none because of the national vaccine shortage.

When she arrived at the Chatham Station store off Route 40, hundreds of people, mostly elderly, already were swarming. "It was just bedlam," Vicchio said.

With the help of Vicchio and other volunteers, the crowd, including some people in wheelchairs, formed a line that snaked through a half-dozen aisles to a table in the center of the store near the Halloween decorations. There, two harried nurses from Maxim Health Systems, a national flu clinic provider based in Columbia, prepared about 300 doses.

"I'm really sorry. I don't know what I can do to help you," nurse Anna Ruby told one latecomer who wanted to sign up for a shot.

The flu clinic Tuesday was one of four scheduled at Giant supermarkets in Howard County this week by Maxim Health Systems. After Saturday, Maxim's remaining vaccine supplies will be administered to high-risk populations in nursing homes, assisted living facilities and doctors' offices, said Steve Wright, Maxim's national director of wellness services.

Elsewhere in Howard, shots have been canceled at senior centers, doctors' offices and even for health care workers at Howard County General Hospital. Flu shots have been scrapped at tomorrow's annual 50+ Expo at Wilde Lake High School in Columbia, where 1,000, or about a fourth of attendees, received flu shots last year.

At this year's expo, county health workers will only be giving advice on how to avoid the flu and administering pneumonia vaccines to people over 65.

Still, Carla Buehler, director of the Ellicott City Senior Center, is facing a steady stream of people asking where they can get flu shots.

"The bottom line is, I don't know where they can get their flu shots," she said.

The vaccine shortage was announced last week after federal officials learned that half the nation's expected supply for the coming winter would not be available because British regulators found possible contamination problems at the Liverpool plant of one of the two U.S. suppliers, Chiron Corp.

The U.S. Centers for Disease Control and Prevention urged last week that only individuals in designated high-risk groups, totaling nearly 100 million people, seek the vaccine.

Some patrons at the Giant said they were surprised the clinic didn't anticipate the heavy turnout. "I can't understand them being caught this unprepared," said Robert Loomis, 75, of Ellicott City.

Yvonne Riggio, 79, of Catonsville said her daughter had told her about the Giant clinic a week ago. She figured that showing up an hour early would be sufficient.

"It wasn't coordinated at all," she said. "People were irate."

Riggio was No. 326 in line.

Meanwhile, phone calls have been flooding into the office of Clarksville pediatrician Paul F. Ambush. Ambush ordered about 120 doses and until about two weeks ago, his supplier had assured him they were on the way. Doctors who did receive their shipments plan to carefully dole them out, primarily to high-risk patients such as infants and toddlers ages 6 months to 23 months and children with a chronic medical condition such as asthma.

"We need them all," said pediatrician Richard Gorman, whose Pediatric Partners in Ellicott City has received its full order of 2,000 doses. Gorman said the Ellicott City office would share doses with its group practice offices in Towson and Bel Air.

Howard County Health Officer Penny Borenstein said the department has only 170 doses on hand, although she has been meeting with other health officers around Maryland to try to secure as many as 4,000 additional doses. That's about half of what the health department intended to administer this season through its public clinics, she said.

Clockwise: Betsy Bracey, left, vents her frustrations while waiting in line for a flu shot at Giant Food in Ellicott City. Maxim Health Care nurse Margaret Christian administers the vaccine to Alice Hegner, who had waited in line since 9 a.m. Nurse Anna Ruby tries to appease the impatient crowd."I'm really sorry. I don't know what I can do to help you," nurse Anna Ruby had to tell a latecomer who wanted the flu vaccine.