By SAM SMITH

November 10, 2002 -- The war on terrorism is about to move to hospital emergency rooms - but it may not be as effective as authorities would like.

State and local officials expect a federal plan for the voluntary vaccination of health care workers against the deadly smallpox virus to be approved this week, with immunization of up to 500,000 workers, including several thousand in New York, beginning in January.

But without the threat of a smallpox outbreak looming, health care workers may refuse to volunteer.

"I would not take the vaccine," said Peter Allar, an emergency room nurse at St. Vincents, who is putting together smallpox educational material for the staff. "I don't think it's a threat at this point."

Experts warn that the smallpox vaccination can be fatal in a small percentage of recipients. Before the United States discontinued smallpox vaccinations in 1972, about 13 people died for every 1 million vaccinated. Several hundred others were sickened.

"I'd rather take my chances than be one of those who dies from the vaccine," said Allar.

It's a legitimate concern, some officials said.

"The vaccine against one of the most deadly diseases in the world is among the most dangerous vaccines in the world," said Columbia University bioethicist Ronald Bayer.

Karen Ballard, director of governmental affairs with the New York State Nurses Association, said if the nurses she represents refuse, it may well not be voluntary for long.

"The hospitals can't allow everybody to not be immunized," she said.