Faced with growing resistance, the Bush administration's smallpox vaccination plan is off to a slow start and may have to be dramatically scaled back.

Eight weeks after the President announced a voluntary program to vaccinate a half-million health-care workers, employee unions are resisting, big hospitals are opting out, and crucial questions about liability and compensation for vaccine side effects remain unanswered.

The Centers for Disease Control and Prevention has shipped 204,000 doses to 40 states, but as of yesterday, only 687 volunteers had rolled up their sleeves - including 97 in New Jersey and four in Pennsylvania. (In Connecticut two weeks ago, state officials were embarrassed when 16 out of 20 health professionals who were supposed to launch the program backed out.)

During a telebriefing yesterday, CDC director Julie L. Gerberding stressed that initial numbers were only estimates, not targets, and that the goal was to have enough vaccinated workers to care for the sick in the event of a smallpox attack.

"We are just in the very early stages of the vaccination program," she said. "We do not have a target number of people to vaccinate. What we have is the targeted capacity to protect the American people.... Our goal is the achievement of a preparedness capacity."

Gerberding said there was a "basement" number for preparedness, but she did not specify the figure. "Keep in mind that preparedness is a process and not an event," she said.

In June, the CDC's Advisory Committee for Immunization practices offered its definition, proposing that 10,000 to 20,000 frontline workers at designated regional medical centers be vaccinated. The committee later endorsed the President's call for a more ambitious program but did not endorse Bush's plan for a second phase, during which the vaccine would be offered to 10 million more workers.

The only dissenter on the committee, Paul A. Offit, head of the vaccine center at Children's Hospital of Philadelphia, said the panel was not pressured by the Bush administration, but "the sense was that the course was already set and we wouldn't make any difference."

Holding back

Offit, who spoke Wednesday at a smallpox seminar presented by the College of Physicians of Philadelphia, explained why he advocates a conservative approach - and why Children's Hospital will not vaccinate any employees:

The vaccine works when given days or weeks after exposure to smallpox, so mass inoculation could still begin after a first case is identified. The virus is not contagious until pox appear a week or two after infection, so there is time to identify and quarantine exposed people. The traditional strategy of quarantining exposed people and vaccinating their contacts helped successfully eradicate smallpox worldwide by 1980.

Most of all, Offit said, the risks of harm from the old-fashioned vaccine - actually a smallpoxlike virus that triggers an immune response - outweigh the theoretical benefit of protection from an unlikely bioterror attack.

Since the inoculation temporarily causes a wound full of smallpoxlike virus, the wound can shed the virus and, in rare cases, accidentally infect unvaccinated people - a disastrous possibility in a hospital full of patients whose immune systems might be compromised.

Opting out

Offit noted that during the last New York City smallpox emergency in 1947, two people were infected and died of the disease - and three people died of the emergency vaccinations administered throughout the city.

Currently, two U.S. soldiers are recovering from complications of smallpox vaccinations. Inoculation is mandatory for military personnel.

After listening to Offit, Adarsh Soni, director of the emergency department at St. Mary Medical Center in Bucks County, said he would not recommend that his hospital vaccinate employees.

"I think this program is not going to take off," he said.

Of the nation's 3,000 hospitals, at least 80 - and counting - have opted out. Last week, the huge St. Barnabas Health Care System, based in North Jersey with eight satellites throughout the state, said it "cannot, in good conscience, participate." So did the Meridian Health System, which includes three South Jersey hospitals.

Many more are on the fence, awaiting answers about liability and disability compensation.

For example, new legislation protects hospitals from lawsuits by vaccinated employees, but not from patients who are accidentally infected by those employees.

Gerberding said she expected government officials to have some answers "very soon."