A steady rain drenched and shivered the region Friday, but Southern Maryland health officials found a silver lining in one recent development: More doses of flu vaccine are on the way.

Federal health officials plan to redistribute 10.3 million influenza vaccine doses to high-risk populations -- such as the elderly and young children -- across the country. In Southern Maryland, where the national vaccine shortage hit hardest in St. Mary's and Charles counties, officials expect their full vaccine orders eventually will be filled.

"I'm very happy, this will allow us to give vaccines to all the nursing homes and veterans homes . . . the high-high risk population," said William Icenhower, the St. Mary's County health officer.

St. Mary's ordered 2,500 doses directly from Chiron Corp., the company that lost 48 million doses last month because of fears over contamination at its plant outside Liverpool, England. A redistribution from other counties in the state provided about 690 doses, but that supply has run out. Icenhower said an additional 1,810 doses of vaccine would come from the state, but he has not been told when they would arrive.

"I know it isn't in our icebox now," he said.

When the vaccine arrives, county officials plan to distribute them to the Charlotte Hall Veterans Home, St. Mary's Nursing Center in Leonardtown and the Bayside Care Center in Lexington Park. During the shortage, the national Centers for Disease Control and Prevention in Atlanta has urged that the vaccine should only be given to high-risk groups such as adults older than 65, children between 6 and 23 months old and pregnant women. But this list will be further prioritized in St. Mary's.

"Being over 65 might not be enough to get the immunization; we're going to try to give it first to people who have lung disease or transplants or are otherwise immuno-compromised," Icenhower said.

Charles County initially received about half of its 4,100-dose vaccination order. An additional 2,000 doses are now expected, said Faye Grillo, the county's deputy health officer. The dates for additional clinics to administer the vaccine will be established when supplies are available, she said.

"People need to continue to call the Health Department," she said. "We will have more clinics."

Maryland will receive an additional 135,000 doses from the upcoming phase of federal distribution, said Greg Reed, program manager for the Maryland Center for Immunization. In a typical year, the public sector in Maryland receives 100,000 to 125,000 doses, he said. About 67,000 doses have come in. The new supplies, which come from a second vaccine manufacturer, Aventis Pasteur, will arrive sporadically until January, he said.

"Our priorities are going to be our long-term care facilities, hospitals, nursing homes and local health facilities, or other places where we've identified gaps or shortages of the vaccine," he said.

Unlike the other counties, Calvert was largely spared from the vaccine shortage. The county ordered and received 15,000 doses this year, about four times more than the usual order, said health officer David L. Rogers. Before the Chiron vaccine had to be destroyed, Calvert health officials had planned to vaccinate all public school students. Then they handed over 7,640 doses to other counties in need.

Calvert's ninth and final flu clinic is planned for Thursday at the Calvert Pines Senior Center in Prince Frederick. The county does not expect to receive additional doses from the state, he said.

"We now have 2,783 doses on hand. I think it's unlikely we'll use up more than 600 or 700 in our clinic next week," Rogers said. "We've had enough to handle our situation so far. We're lucky."

Nurse Jeannette Loving, right, administers a flu shot to Mary Dillon at a health fair last month in St. Mary's County.