The number of health care workers in Minnesota lining up to get the smallpox vaccine is falling short of expectations, according to hospitals and public health agencies.

Even as concerns about the plan continued to build in Minnesota and nationwide, federal officials said they will move ahead as scheduled.

The Minnesota Health Department said Friday that it still has time to recruit more volunteers before the first round of vaccinations begins, possibly as early as next month. About 50 hospitals across the state had estimated earlier that as many as 5,300 workers would get vaccinated -- a number that may prove unrealistic.

At St. Cloud Hospital, for example, only 22 health workers have volunteered so far for the smallpox vaccines -- about one-tenth of the 210 originally projected, said spokeswoman Jeanine Nistler. However, some hospitals said they are on track.

Officials of some unions and hospitals said employees are worried about the risk of the vaccine, and the financial consequences if they get sick.

"I think that people really are a little unsure of what's the right thing to do," said Anne Sonnee, spokeswoman for HealthEast Care System, which owns St. Joseph's Hospital in St. Paul, St. John's Hospital in Maplewood and Woodwinds Medical Campus in Woodbury.

On Friday, the Institute of Medicine, an advisory group to the federal government, urged federal health officials to proceed more cautiously and deliberately. It said the government should respond to concerns about how people will be compensated for medical expenses and other losses, and it should clarify the risks to potential volunteers.

Also this week, three national health care unions called on the government to delay the plan until those concerns are resolved.

Yet officials from the U.S. Centers for Disease Control and Prevention (CDC) responded Friday by saying that they will move forward as planned, and begin shipping the vaccine Tuesday.

"We intend to make this program happen on time," said Dr. Julie Gerberding, CDC director. "We . . . live in a dangerous world these days where a terrorist attack with smallpox is possible. We have to protect the people."

The CDC has made "heroic efforts" to protect health care workers who get the vaccine, she said. At first, only those who would care for patients in a smallpox outbreak will be eligible for the vaccine. Later, it would be offered to other health care and emergency workers and eventually to the public.

She declined to say how many volunteers have stepped forward nationally, but she said that states have requested 50,000 doses of vaccine for the first round of vaccinations, which could begin nationally as soon as next week. So far 11 states have asked the CDC to begin shipping the vaccine, but she declined to say which ones.

Minnesota health officials said they have not yet requested a shipment.

Buddy Ferguson, spokesman for the state Health Department, said that hospitals are revising their estimates, and that the number to be vaccinated could change.

"I don't think we are concerned at this point that we won't be able to vaccinate enough people," he added.

Fairview Health Services, which operates seven hospitals, has seen fewer volunteers than predicted.

"Generally we have not hit our goal," said Alison Page, Fairview's vice president for patient safety.

Although she wouldn't disclose the number of volunteers, she said officials had predicted 100 to 200 at each eligible hospital.

"Certainly we want our employees to be very careful," she said. At the same time, "we are not anticipating at this point any of our hospitals pulling out of the process."

Meanwhile, three east metro counties had expected 1,500 volunteers from among their public health workers; about 1,000 have stepped forward so far, said Lillian McDonald of the St. Paul-Ramsey County Health Department.

In Duluth, a tuberculosis case forced two hospitals to put off recruiting volunteers for the smallpox vaccine. St. Mary's and Miller-Dwan hospitals soon will test health workers for TB because a doctor fell ill in December. The smallpox vaccine can taint the results, said Dr. Timothy Burke, medical epidemiologist for the hospitals. For now, the TB tests should take priority, he said, "because that's something that's real, it's right here, and the smallpox is theoretical."

Some hospitals, though, say they're on track to meet their goals. Abbott Northwestern in Minneapolis already has about 100 volunteers, and Hennepin County Medical Center in Minneapolis is close to meeting its goal, officials say.

In Minnesota, the nurses union is advising members to do their homework before making a decision. "Before you volunteer for anything, make sure you're informed and educated on the risks," said Walter Frederickson, head of labor relations for the Minnesota Nurses Association. "Because of the voluntary nature, it's your risk."

The American Nurses Association called on President Bush Friday to delay the smallpox plan, joining two national unions: the Service Employees International Union and the American Federation of State County and Municipal Employees.

It is not certain how many are reluctant to volunteer because of the vaccine's health risks or because their health status precludes them from getting the vaccine. Because vaccinated people can shed the virus, family members also may be at risk.

That does not stop some, however.

"I have to make sure that the [vaccination] site stays covered," said Jeff Allen, a St. Paul-Ramsey County nurse who has volunteered for the vaccination. He said he discussed the risks with his children and told them, "If we are sitting on couch snuggling, we have to be careful."

Vaccine experts say 20 to 30 percent of the population could be ineligible because of medical conditions, such as eczema or pregnancy.

Even if the number of volunteers in Minnesota is lower than expected, it would not handicap the state's efforts to prepare for a bioterrorist attack, said Ferguson of the Health Department.

"The idea here is to have minimal numbers of people vaccinated in advance of an actual event so they could respond to it," he said. "But again, you can vaccinate people even after they've been exposed to smallpox. That's the backup."

-- Staff writer Jill Burcum contributed to this story.

-- Josphine Marcotty is at marcotty@startribune.com.-- Maura Lerner is at mlerner@startribune.com.