Hoping to get immunized against a possible sniffling, head-aching, won't go away winter flu? Good luck, say local health care officials, who have lately been so inundated with requests that they've been suffering shortages of the vaccine and have been forced to order additional supplies from manufacturers.

Demand for the vaccine has increased by nearly 300 percent this year at University Health Services (UHS) and at the Massachusetts General Hospital (MGH), according to UHS Director Dr. David S. Rosenthal '59 and Nancy S. Bryant, head unit nurse at the MGH medical walk-in clinic. Cambridge Hospital and Beth Israel officials also cite heavy demands.

"We've given close to 2,000 vaccines to employees of MGH and we ran out last week," says Linda Thomas, a employee health nurse at MGH.

Other organizations cite similar shortages. Kate McCormack, a spokesperson for the Massachusetts Department of Public Health, says that the department's order of 475,000 units for the entire state was inadequate and that 25,000 extra doses had to be obtained.

But why such an increased demand? "For a long time many people were not open to getting a vaccine--especially a flu vaccine--because they thought they could get the flu from it," suggests McCormack. "Finally, people are becoming more responsive to getting the vaccine."

This is also the first year that Medicare, the federal program which provides funds for elderly patients, has provided the vaccine free to those elderly people at greatest risk.

The vaccine, which works by "priming" the body's immune system against subsequent infection by the virus, is recommended for certain target populations: those who have autoimmune deficiencies, are over 65 or who have chronic medical conditions such as asthma and heart disease. The population also includes doctors, nurses, medical students and other health care workers who could potentially expose themselves or their patients to the virus.

But the shortages may have been exacerbated by some healthy individuals, not included in the target population, who have also rushed to be vaccinated and avoid the aches and pains associated with influenza. Most experts, however, do not recommend that the general public be vaccinated.

Dr. Larry C. Madoff, assistant professor of medicine at the Medical School and a specialist in infectious diseases at Beth Israel Hospital, urges the public to avoid vaccination, which can be risky.

"It hurts, it's inconvenient, it takes time," says Madoff. "For those who need the vaccine, the very small risk of a vaccine is worth it. But for normal, healthy people it's a close call."

Madoff recommends that limited vaccine supplies should be reserved for those who need it the most.

Dr. Dennis L. Kasper, Channing professor of medicine at the Medical School, agrees with Madoff's suggestion.

"The recommendation has not come out for every one to get the vaccine," says Kasper, who also serves as chief of infectious diseases at Beth Israel. "I think it would be imprudent of us to recommend otherwise."

This year's surge in requests for vaccinations came after a late August announcement by the Centers for Disease Control (CDC) regarding the detection of the type A-Beijing strain of influenza in Louisiana.

The type A-Beijing strain, along with the A-Texas and the B-Panama strains, are the three influenza viruses against which this year's vaccine has been formulated to protect.