The association joins a growing number of health-care organizations and hospitals nationwide that have expressed reservations about President Bush's plan to inoculate some of the nation's front-line health-care workers.

As part of its preparations for a war with Iraq or a terrorist attack, the administration's voluntary plan calls for 500,000 health-care workers to be vaccinated. A second phase of inoculations, which can prevent smallpox if given before or shortly after exposure to the disease, is to include 10 million health-care workers, firefighters, police and emergency personnel.

The concerns are prompted in part by the possibility of rare but potentially more serious side effects with the vaccine.

The inoculations are expected to begin this month. Nancy Rubino, president of the Delaware nurses group, said the association wants the inoculations delayed until its concerns are addressed. The group is worried that others might inadvertently be infected by the live-virus vaccine and that workers may not be compensated if they miss work because of the vaccine or if they suffer side effects.

Experts estimate that 15 to 43 out of every million people being vaccinated for the first time will face serious complications, and one or two will die. The vaccine is particularly risky for pregnant women and those with a history of skin problems or weak immune systems, including people with HIV, cancer and those who have had an organ transplant. Recently vaccinated people may also pose a threat of infection to others because for several weeks they shed the live virus used in the vaccine.

Health workers who take the vaccine cover the injection area with a special patch and are told to wash their hands frequently.

"We want them to have their questions answered so they can make an informed decision," said Rubino, whose association represents about 600 nurses in Delaware.

Carol Stephens, 49, a pediatric nurse at Kent General Hospital in Dover, said the call for a delay makes sense. "I need to know more about it," said Stephens, who is not an association member. "I need to know how safe it is as far as a reaction."

Not everyone seeks a delay. Dr. Sue Kost, 41, an emergency room doctor at the Alfred I. du Pont Hospital for Children, said she would not hesitate to get the shot.

"We used to routinely vaccinate everyone for smallpox," she said. "The risks were exactly the same as they are right now. It hasn't become a more dangerous vaccine, but I think people's perception of it is that it is a more dangerous vaccine. I guess we're a more paranoid society these days."

But people who would be vaccinated have raised legitimate concerns, she added, including worries about what happens in the aftermath of a bad reaction to the vaccine. "If people miss work, will they be paid for that? I agree there are things that aren't well thought out."

Kost said the hospital has not asked her to volunteer for the vaccine. But hospital spokesman Jim Lardear said about 45 doctors, nurses and other medical personnel have signed consent forms to receive the vaccine.

Carl Kanefsky, a spokesman for the Medical Society of Delaware, which represents about 1,700 doctors, said he has not heard concerns from members about the inoculation plan.

Division of Public Health spokeswoman Heidi Truschel-Light said the state's vaccine shipment arrived here Tuesday, and she expects the vaccinations to begin by March.

About 720 health-care workers in Delaware are to receive the vaccine, including hospital emergency personnel, said Dr. Paul Silverman, chief of disease prevention and control in the state's Division of Public Health. That number is likely to dip because the program is voluntary, and some workers might be excluded because they have conditions that would put them at greater risk, he said.

All 50 states have submitted inoculation plans and their applications have been accepted, said Llelwyn Grant, a spokes- man for the federal Centers for Disease Control and Prevention in Atlanta. On Jan. 24, four doctors were vaccinated in Connecticut, the first state to participate in the program. But 16 volunteers who were scheduled to get shots with them backed out.

Several national unions and other groups have criticized the program, including the Service Employees International Union, with 750,000 health-care workers among its members. The American Nurses Association has 153,000 members.

The Children's Hospital of Philadelphia, the nation's largest children's hospital, also announced recently that it would not participate in the program, joining at least 80 other hospitals nationwide that have made similar decisions.

A recent USA Today/CNN Gallup poll reported that 53 percent of people surveyed said hospitals that refuse to take part in the vaccination program are "doing the right thing," compared with 39 percent who said it is wrong. Eight percent said they had no opinion.

Before the program can begin in Delaware, Silverman said health-care workers here must be trained to give the smallpox vaccination, which has not been used routinely since 1972 and is injected differently than other vaccines. One of those differences is the use of a two-pronged needle.

Health-care workers also must be trained to spot symptoms of an adverse reaction to the smallpox vaccine, he said.

Dr. Charles Smith, president and chief executive officer of Christiana Care Health System, said lectures about the disease already have become a part of the program there. They were instituted because most doctors and nurses in the United States have never seen cases of smallpox. The last known case in the country was in 1949.

About 150 employees at Christiana Hospital and Wilmington Hospital, two hospitals operated by the Christiana Care Health System, will be asked to take the vaccine, he said.

Smith said he shares concerns about the possibility workers would suffer adverse reactions to the shot, but serious complications are rare, steps will be taken to minimize the risks and workers have the right to decline the vaccination.

Reach Edward L. Kenney at 324-2891 or ekenney@delawareonline.com.