(CBS) There is new concern about the government's already troubled smallpox vaccination program. Few of the half-million healthcare workers eligible for innoculation under phase one of the program chose to get vaccinated.

And some healh experts are warning -- not so fast.

Some states, including Florida and Virginia, are already moving ahead with phase two of the government's smallpox vaccination program, to include as many as three million firefighters, police and paramedics.

But a new report issued by an Institute of Medicine panel says all civilian vaccinations should temporarily stop, and that the federal government should actively get out the word to states, CBS News Correspondent Sharyl Attkisson reports.

The Committee on Smallpox Vaccine Implementation earlier recommended a "pause" in civilian smallpox vaccination, in part due to unexpected adverse events emerging in what was already known to be the most toxic vaccine on the market.

The head of the committee, Dr. Brian Strom, says the Centers for Disease Control, which advises states on their vaccine programs, recently accepted the idea of a pause. Yet, Strom says, the CDC didn't explicitly notify states of this change of heart. Tuesday's report encourages the CDC to take more action.

"What we're asking is one step further – that they go out of their way to make it easy for those states who want to pause to make it easy for them to be able do that," says Strom.

"We think that it's better for public health, we think it's better for the campaign, that all information be learned about to the degree possible before launching into phase two in a large-scale way. We thought that it was very important that people stop, they take stock of where they are, look to learn from the experience gained today before proceeding onward with the rest of the campaign."

The report says several issues should be resolved "before deciding whether and how to proceed with vaccination."

On the issue of safety, the report says a "pause" is needed to collect and evaluate adverse event reports. Although every civilian who receives the smallpox vaccine is supposed to be individually tracked, only 34 percent of vaccinees have made it into the surveillance system so far; two-thirds have not.

"Some adverse events might not arouse concern on a state level, but aggregated nationally, new patterns could emerge," says the report. "Cardiac complications were unexpected adverse events, and there may be others."

Says Strom: "At this point only about one-third of the civilian patients who've gotten the vaccination are in the surveillance system. And one of the things we'd like know about is the outcomes in the other two-thirds of the patients."

The report also says the consent forms and educational materials should be revised with updated material and information that can be understood clearly by firefighters, police and paramedics instead of the health care workers who were targeted in phase one.

"In many ways, the most important message we have is that maximum preparedness doesn't require huge numbers; it requires it be done very safely and very carefully. That's what's been done so far. The CDC has done a terrific job. And the CDC should use (a pause in the state's vaccination programs) as an opportunity to learn maximally from the experience to date, in order to be sure that as we launch into phase two it's given to the right people, it's the right size and it's done as safely as possible," says Strom.

The panel that issued the new report was created by the Institute of Medicine to advise the federal government on implementing the smallpox vaccine program.

But it's unclear whether the federal government will take the committee's advice to publicly encourage states to "pause." Doing so would highlight touchy subjects in some political circles: unexpected adverse events, and what some view as the lackluster response to President Bush's smallpox vaccine program. Out of roughly 500,000 eligible health care workers, only a small fraction, 30,000, volunteered to receive the vaccine in phase one.

Many who refused the vaccine were concerned about the vaccine's risks. Some states have already stopped their smallpox vaccination programs on their own, others are "skipping" phase two altogether.

The inherent conflict involved in this issue is apparent. Strom, chair of the committee that wrote the new report, told CBS News it was issued quickly because of its importance and urgency. Yet a spokesman for the Institute of Medicine told reporters, in advance, there would be nothing particularly newsworthy in the committee's report.