By LAWRENCE K. ALTMAN

mallpox vaccine should be made available to certain groups of health care workers like those in emergency rooms even before a bioterrorist attack, a number of speakers said yesterday at a forum on vaccination policy.

The speakers, at a government-sponsored forum at the Mount Sinai Medical Center in Manhattan, many of whom were doctors, nurses and other health care workers, said they needed protection because, if an attack occurred, they would most likely be the first to care for patients.

The forum was the first in a national series that the Centers for Disease Control and Prevention is holding to solicit opinions before two advisory committees decide whether to change recommendations on smallpox vaccination because of the bioterrorism threat and the availability of additional vaccine.

The current recommendation is that vaccine be given just to the small number of scientists and laboratory workers who work with smallpox and closely related viruses. The advisory panels are considering whether changes are needed, in particular whether the entire population should be vaccinated or just health care and other emergency workers.

The panels, the Advisory Committee on Immunization Practices and the National Vaccine Advisory Committee, are generally expected to make their decision by June 20.

The fairness of offering vaccine to one group and not to the population at large is an issue that the panels will consider before their decision, a spokesman for disease control centers, Glen Nowak, said. The committees will be guided by standard public health policy, which calls for weighing the benefits of vaccinating a specific group, or the general public, against the risk of complications. Determining the balance is particularly difficult because the disease would not be naturally transmitted, and the benefit is to protect against a theoretical risk, a bioterrorist attack.

One factor is that health care workers would most likely have a greater risk of exposure to smallpox than the average citizen. In deciding, the panels will want to avoid putting any group, or the public at large, at unnecessary risk, Dr. Nowak said.

At the New York forum, few speakers said they favored vaccinating the public because of the risks of the vaccine. The vaccine is probably the most dangerous one. It can cause serious problems like generalized rashes, brain damage and death. It poses risks to vaccinated people and to those with whom they come in contact.

As many as 38 million Americans would be at serious risk of complications from smallpox vaccine because they are infected with H.I.V., have cancer or other diseases causing impaired immune systems or have or have had common skin conditions like eczema and atopic dermatitis.

"We heard a great diversity of views," Dr. Guthrie S. Birkhead, a New York State health official and a member of the committees, said in summarizing the forum.

The committees are basing their thinking on the assumption that the government has not learned of a specific new threat, Dr. Birkhead said. But a broader recommendation would take effect if laboratory workers identified the virus or doctors diagnosed a single case somewhere in the world, he added.

The meeting in New York and one yesterday in San Francisco were extraordinary because the disease was eradicated 20 years ago and routine vaccinations stopped in the United States in 1971.

Many younger participants at the forum said they had never given a smallpox vaccination, seen the disease or been vaccinated. Older participants like Dr. Walter Orenstein, who directs the national immunization program of the disease control centers, said, "I never thought I'd be talking about smallpox except in an historical context."

After the anthrax attacks last fall, the government expanded its smallpox vaccine stockpile. Tests have shown that the 15 million doses stored frozen since vaccinations stopped can be safely diluted to 75 million while retaining potency. A drug company, Aventis Pasteur, has donated 80 million doses that it has kept frozen since 1958. The government says that supply will be used only in an emergency.

The government is also buying 220 million doses made by a new technique. Delivery is expected by year's end. Because none of the vaccine is licensed, its use would require signed consent from each recipient.

The expanded supply has led officials to consider broader options in vaccinating segments of the public. Deciding which segments and how many participants is one of the thorniest public health problems, largely because no one can predict if, when and where an attack might occur and where the victims might seek care.